Well i can see both sides of the discussion,but from my point of view,buying different capacity's of mags for various weapons becomes very costly as i dont have the best paid job in the world(nhs laundry worker).saying that my first game was 'Autumn Mist' & i only had the one hi-cap + one mid-cap so didn't have much of a choice but i will be saving up for three 190rnd mags,which i have for my vietnam loadout.
On the subject of th '600rnd' limit,i think its a fair amount to have as david said your in the game a bit longer but if you lower the amount i'd imagine you'd be visiting the regen a bit more often.i've attended a few themed games in the past including vietnam themed & they have had '600rnd' limits & i think its worked well.
600 rounds is good, I find it dificult to get even 1/2 that off before I get killed, low caps in mp40s are fun,
Steve.D
BUT. There is one thing that applies to both Hicaps and Locaps, and I observed it at BOTB2. Ammo conservation, or to be more precise, the lack of it.
wouldnt be refering to my style of, " a full mag from the hip in the general direction of the enemy" ???? 
"Take that you rotton helping of strawberry flan!"
Joseph Porta to "strawberrys and cream", in the sven hassel book ,ogpu prison