A version of the Lee-Enfield SMLE is still in use with the Indian Police Force (and I think their border force?) and Blücher was sunk by 19th century coastal defences in 1940, I agree that obsolete does not mean useless and it certainly doesn't mean harmless. For certain uses (training, border security, issuing to 'unreliable' troops) obsolete equipment might even be preferable. Warfighting is rarely one of those cases.
For that reason militaries do not typically buy obsolete equipment. A 7.62 bolt action rifle will absolutely kill a man, but try issuing them to the US Marine Corp and see the response. Try suggesting that the US Army should readopt the Sherman... Issuing your troops inferior kit typically achieves three things,
- Kills your troops morale
- Looks very bad in the papers
- Gets your troops killed
One on one, Clan mechs kill equivalent Inner Sphere mechs, their weaponry is simply superior. If you could close that technological gap, why wouldn't you?
Cost, I don't think should be an issue for House militaries, and even mercenaries to an extent. The majority of a mech's cost is determined by its tonnage and its engine rating, doubling the weapons cost wouldn't likely shift the needle that much.
Maintenance and ease of procurement absolutely should be an issue and that is why I tended to avoid too much mixed tech in the 3050-3067 era. I absolutely agree with the rules that make it harder to maintain a jury rigged mixed tech mech than a factory standard machine, but that is also my point in the post 3145 era. Once you have mixed tech mechs being produced in a factory, using factory produced (i.e. not salvaged) clan components, why should those be harder to maintain? As far as I am aware, Clan tech isn't harder to maintain, its harder for a Inner Sphere techies to maintain because they are not trained on it, don't have the manuals or the spare parts. I don't see that that should hold true in 3145.
ColBosch's "invalid" reasons are worth considering as well. 'Tradition', 'familiarity', 'bureaucracy', 'reactionaries', 'budgets' are all historical reasons for militaries marching to war with 'last years' weaponry. I could definitely see a few units/houses insisting on using existing weapons for any of the above reasons. That said, none of those are good reasons, and history looks poorly on militaries that have left their troops in possession of inferior weapons when the shooting starts.
The difference between giving a technician a fixed wrench and a tank crew a T-34 is the fixed wrench is very unlikely to get the technician killed. The T-34 will absolutely get its crew killed if it goes anywhere near the shooting.
Challenger