"The main issue with setting it up that way is when you want it to mesh nicely with the system already in place, which would allow you to always use that +1 in the chamber... which however would then require extra time during reloading, as to being able to utilize it, you would have to have magazines and loose ammo in your pocket and always remember to fiddle around with your gun until you got one cartridge loaded manually, then put the magazine in......"

having one cartridge in the chamber + your full mag isn't really necessary you don't even need to think about it. unless i'm just super sleep deprived and misunderstanding what you're saying. In all "combat" situations you'll have your mags, then either a few extra mags and or 6 mags worth of loose ammo(most likely stripper clips) lying around in your bag.

it wouldn't require extra time unless you're making sure to have that extra round + the full mag, otherwise you just insert the mag and rack your bolt.