Well, the companion has some options for the vehicle trait, the most interesting being that it also give qualifications for that size 'mech. What I don't like is that it's a new penalty for not having rather than an advantage for having the vehicle trait.
It all come down to the basic rules for GMing: If it's not an advantage, it's not a positive trait - give the points back. If it's not a disadvantage, it's not a negative trait - take the points back.
For example if a group of players are going to form their own Merc Company with just them, the Vehicle trait with owned 'Mechs is an advantage in the short term at least, but the points they put into Rank no longer apply. Each character has gone through (rpresumably) millitary training and probably even tours of duty, each time earning points towards Rank. After mustering out, however, they can no longer order reg troops around or requisition parts or any of the other advantages that rank gives. Either give the points back or convert them to - say - Connections or some such.
- Shane
The thing there is... that rank is always going to be there. Even after mustering out or retiring, a character is going to always be known for having that rank. There is almost a certain... I can't pick the right term for it... but an air about them. If someone is a retired colonel, they will always be that and it will have an effect amongst those both in and out of the service if they know of the character or that character decides to put his foot down. It comes with a modicum of respect.
You can see it in certain environments... I know I have seen it happen. The room may be filled with a bunch of retired folk and thus are all on the same level now as civilians but damn it, the room sure came to a halt quick when the old captain put his foot down and brought order to the chaos of the event that was happening. Perhaps that is just my own experience but I think people who know better just have a level of respect for someone who has earned their rank.
So while it is not an advantage being currently used in the case of a retired military character, the fact that they may be called back up (it has happened numerous times in history) means that the advantage is there. They shouldn't get an immediate return on those points. They should have connections but they are informal connections, not the proper connections that the advantage provides. Connections usually means useful allies, not the kind that you might have as acquaintances or people you knew in the service.
Now, as for the mech situation... the fact that a player once owned a mech means they have a record with that mech. If they paid points for it, it might mean that if the player plays their cards right... they can try to get something to make up for it. After all, if you were someone in charge of the logistics and supply of the army, you would trust someone who lost a heavy mech in combat, who had a history of driving them effectively, who was loyal and trustworthy, and didn't lose their mech through gross negligence with a new one if they put in the proper requisition forms and went through all the proper steps of getting it through the national government. Would they own it like their old mech and have it customized like their old mech? Hell no. Sorry, those points went bye bye but if they are actually proper soldiers and not merc scum, there are ways around even my previously stated cut throat bloody attitude.
And yes, if they are a merc and not part of a major outfit... no luck or mercy. They want to be lone wolves out for cold hard cash... kill them like the honorless dogs they want to be.
Same thing goes for if they had a customized mech or vehicle. It means they have experience with keeping modified equipment running so that way they have a bit more pull in getting modifications if they go through the proper hoops to do so.
But no... don't give them points back. Trust me... if you give them points to be spent as they want, you will see wild swings in a character's abilities. Had a GM recently do this in a different game that uses point by skills and abilities and that sudden freeing up of a significant portion of XP suddenly through the game's balance and party capabilities right out the window because once the game is started, players will know the focus of the game and giving them a huge chunk to spend (and the points for a customized mech is just that) will allow them to further specialize into the focus of the campaign and further unbalance things.
Trust me, if I knew I could take a custom heavy mech early game and if I lost it, I was going to get those XP back... I would game the HELL out of the system in a heart beat. And I know a good corps of players who would do the same thing. Same thing goes for getting a new mech to replace the one they lost because they had the advantage, I would abuse that to no degree, not being nearly as conservative as I would otherwise be. If I knew I would get another mech as long as I didn't sell it off, lose it in a poker game, or just be stupid... I would be the most fool hardy, risk taking bastard this side of creation. Why be safe? It isn't like what I have is of value to me... I am just going to get another one eventually.
That is why I am a huge advocate for not giving any points back. If they thought that a skill or advantage would be good and they were not skilled enough players to utilize that advantage or skill, that is their fault. The blame is entirely on their shoulders. If luck of the dice removes an advantage, that is luck. Help them out some as a GM, even a cut throat bastard of a GM like myself has to keep the story going somehow, but make them at least work for getting it back... don't be a monty hall gm and give it to them without some work.
But never give XP back.
The party dynamic past the first few adventures will have grown around the strengths and weaknesses within a group. Refunded XP disrupts that party balance by allowing players who get them to backfill those weaknesses or further advance their strengths... either putting them further above the norm and overshadowing the game or making everyone equally bland and level... both of which is not fun.
You also don't make players pay for advantages they earn through game play. If a player actually earns through play land and a title... you don't make them pay hundreds of XP for it. That puts him in an XP debt that actually penalizes a player for good play. If a dispossessed mechwarrior steals a prototype mech or rebuilds a salvaged one through play, you don't make them pay for it either because that also puts them XP debt where they are not advancing like everyone else.
Trust me... it is no fun to watch a player sit knowing that their XP for the next two to five sessions is being pre-spent to pay for an award they earned. I have seen GMs do that. It does not sit well with them and that bad attitude will be like a poison which will infect the rest of the group... not immediately but it always does.