I have suggested on many occasion that infiltration units should be available in two ways.
Build able from HQ at normal price and spawning from ambient buildings with paying a premium for the instant production and on field deployment.
Think that would fix the issues with infiltration Commandos.
I like that. I think having rifles upon infiltration spawn is a better solution than a 3 man squad though. That way the infiltration spawn still takes planning and thinking ahead but doesn’t punish the British player for using it.
I believe that would also make commando weapon teams, manned by infiltration commandos, armed with their default rifles instead of STENs. Personally I like this as a change, except I would give them M1 carbines instead of Lee-Enfields as it is more suitable as a commando weapon and it is highly likely that special troops like Commandos would have access to US weapons like the M1 carbine. This way infiltration commandos get a mid range weapon that isn’t OP and can still upgrade to their really strong SMGs later. When manning a weapon team they would revert to their Carbines and thus be less dangerous to flanking squads. Additionally, and I think most importantly, it would allow 5 man infiltration commandos to be sneaky, dangerous and still survivable while not being too strong. This would encourage aggressive commando spawning because they would be survivesnle at 5 men, but not be too strong with just M1 Carbines.
Basically it’s a win-win. Axis doesn’t get clobbered by OP commandos popping out of buildings, but Allies still gets to try commando pops without being heavily punished by the risk.
Also if you want to make the infiltration commandos even more interesting, you call them SAS infiltration squads or SOE infiltration squads and make them upgrade from M1 Carbines to having three or four Thompsons plus Carbines. This would make them thematically different but still filling the same role as they currently do, while also satisfying the desire for Commandos to have tommy guns.
(Historically Commandos really favored the Thompson, although for them it was usually the earlier M1928A model, not the M1A1 in game and it was primarily because the Thompson was commercially available from the US at the time and STENs we’re still not yet in mass production. )
I like the idea of the SAS infiltration squad, but giving them M1 carbines with the same stats as paratroopers and rangers upon spawning from infiltration would still be a bit strong (keep in mind that these M1 carbines are different from the rear echelon ones and are straight up better than the riflemen’s garands). I would suggest still making them spawn with Lee Enfields, which are worse on the move and shoot slower, and then give them an upgrade that gives them 3 Thompsons and 2 M1 carbines, but that locks out brens because their brens would be OP in conjunction with Thompsons.
Since commandos have access to 2 "super brens" having M1 rifles or Thompson (with profiles similar to USF ones) will simply make them OP.
Being able to built from HQ for a normal price is a simpler solution.
Well if they were given Thompsons it should lock out both weapon slots assuming there were 3 Thompsons and 2 carbines in the squad total.
TL; DR of the various opinions in my responses:
Make commandos buildable from HQ at normal cost as vipper said, but let infiltration spawns spawn at 5 men with Lee enfields and have a free upgrade to stens.
Alternatively, and (IMO) more interetingly, as GI John 412 wrote, rename them as SAS infiltration squads and give them Lee enfields upon spawning (including from infiltration) and give them an upgrade for like 60 muni that gives them 3 Thompsons and 2 M1 carbines and locks out both weapon slots. Spawning from infiltration with 5 M1 carbines would be a bit OP though.