With regard to treg's post, I don't care what holster type I use. Some things hold constant:
1) each type of carry has vulnerabilities for grab defense. For instance, the rear cant he likes makes a snatch from behind much easier than from a straight drop, and a rear snatch is easier from a straight drop than from a forward cant. The user should familiarize himself with the vulnerabilities of whatever system he uses - and for many of us, there are multiple potential systems.
2) if I rely on draw speed to resolve the issue, and not on movement, then I am probably more likely to get stabbed, sliced, struck, or shot. I train to draw while moving. Movement options include forward or rear diagonals, pivots, parries and redirects, and/or physical engagement - plus draw as appropriate.
3) some carry types have other restrictions. Pocket carry is not friendly to seated draws. Then again, neither is treg's rearward cant. See comments in 1) above.