Well in one form or another I have been using MegaMek since the first years of its stable release. (It's very hard to find local players in rural areas so online is my only option.)
I have been, and still am, very impressed and pleased with all the hard work done by the developers and community surrounding the whole suite of assets they have given us. Yet perhaps I have a rather unique situation that does not come from anything the developers have done but simply my own use of the program.
I was super excited when MekHQ came on the scene and quickly began gathering all my eggs in one basket pulling together and solidifying all the various little TO&E's I had made over many years (.mul files saved at the company level) into one big grand army.
After years of establishing different companys, battalions, regiments, etc I finally could have them all in one file to much more easily transfer resources, individual units, and personnel around not to mention better record personnel records, kills/losses, battle reports and easily mark the passage of time.
Needless to say fleshing out random names and organizing details on every single soldier and unit has been a labor of love that has taken years to complete in bits of spare time and still remains a task to catch up on from my 1000's of .mul company level files of old. I am roughly about 3/4's through.
With MekHQ, perhaps unlike most people, I am not running a real RPG campaign of sorts but just recording my battles with other human players, deploying forces, salvaging off my victories and replacing losses any time I am defeated. My daily or weekly matches with others is my campaign with the clock set 10000 years in the future so that Saturday April 7th, 2018 is basically Saturday April 7th, 12018 and I can record the passage of time accurately.
Needless to say given the title of my thread I have hit a wall with just how many units one can fit in a single campaign file. I can only set the given RAM resources so high after all and trust me this computer is pretty top notch quality. It only seems to struggle with loading the file when opening the program (and lately it just can't before running out of resources otherwise running the program is fine and not really that slow at all.)
I am sure my save would be in the top 1% for largest size taking over an hour to load some days if and when my computer restarts. The .cpnx file alone is just under 1 GB at 994MB.
My "active" force consists of currently 17,655 units out of a planned 22,965 (not including captured units) in 122 different regimental commands (or equivalents). Cambo's Clan Wolf TO&E clocks in around 1,440 "active" units.
No one else has come forth anywhere else with a TO&E anywhere near as large but have reported similar RAM issues and gave me suggestions that let me continue adding, editing and fighting for awhile longer.
Sadly I have come to the conclusion I can no longer move forward with just one all encompassing file and will once again have to split up my military into smaller less hardware demanding chunks. Given the freedom I had with having one ease of editing campaign file till now it is a bitter pill to swallow for convenience sake but there is nothing that can be done about it.
Usually I simply organize things at the regimental level and haven't focused to much on dedicated divisional levels or higher as I very rarely have to call upon that many units for one battle. Therefore I am wondering what might be the best option? Having separate regimental, divisional or corps sized files? I remember back before MekHQ having more than one file dangerous as I have often saved over the wrong one in the past wiping out entire companies of units with a miss-click of the mouse. (I learned quickly to implement backups but even then the odd accident occurred.)
I also have fully fleshed out support assets as well, recon, engineers, artillery regiments, transport and logistics regiments, field ambulance units, even military police and POW transport detachments, should those be attached with various commands or in their own "support" file. I dread having to "transfer" bulk units back and forth from file to file for R&R times or finding and transferring long lists of supplies carried by various logistics commands to units who just saw action. About the only thing I don't track is the kitchen sink (ie: human needs like food, water, field kitchens, replacement personnel transport, and mortuary affairs logistics.)
Suffice to say RAM's a royal pain and I may be an idiot but at least I was having fun. ;)