I saw this over at the Heartless Libertarian this morning:
Breaking down the "Combat" or "Straight Thumb" grip.
Of course it SHOULD be the best discussion about it; it's with Brian Enos, one of the guys who "invented" it. I've actually spoken with Brian about this a bit, read his book, seen a couple videos etc...
The straight thumb grip is one of the variants of the high, forward, thumb over thumb grip; as opposed to the "Gunsite grip", or the "low thumb over thumb" where the support hand thumb is actually curled on top of the dominant hand thumb (I only recommend this grip for shooting revolvers, were it works very well).
I've mentioned this grip before; and that I had for years generally used the gas pedal grip (a variant of this where the dominant thumb rides the safety and the support thumb indexes on the slide stop pin) on my 1911s, and just whatever grip worked for my other guns.
A couple years ago I switched to the Plaxco grip (a variant of the above where your support hand index finger wraps around the trigger guard), because the Plaxco grip works for guns where the straight thumb grip doesn't (a lot of guns other than the 1911); because it rotates the support thumb out and down a bit, away from the slide stop (some guns, like the BHP, can have an accidental stoppage under recoil if your thumb is in the wrong spot). I prefer using the same grip on all my guns if possible, and I shoot guns other than a 1911 on occasion.
Honestly, in my testing out of various grips, the Plaxco grip hadnt been any slower or less accurate than the way I was doing the straight thumb grip. Maybe a bit less, but the advantage of not having to change grips for different guns outweighed that for me.
When I was in Texas though, Len Baxley showed me a little change on the way I was shooting straight thumb, literally a quarter inch move in one direction and a quarter inch in another, that shrunk my rapid fire group sizes with my 10mm in half.
It didn't make as much difference with the .45s; but it was still better.
Unfortunately that still leaves me with two different grips for my different guns; but I think I can train around the problem; especially since I now have an ultra compact 1911 to use as my small concealment gun.
It probably means I won't shoot my other guns quite as well as I shoot my 1911s, but honestly, I'm good enough for defensive purposes with my other guns whatever grip I use (well, assuming it's a proper grip anyway.. not shooting gangsta or anything); and if I'm concerned about my best possible shooting, I'm shooting a 1911 anyway.
Given it's a very small tradeoff on the other guns for a big improvement with the 1911, it makes sense to me to shoot the best that I can with my primary defensive pistols, rather than try and generalize to all my pistols.
The good news is that the straight thumb grip works fine with my USP compact (actually the accessory rail groove makes a great indexing point), which is my other primary carry that isn't a 1911; but on the Hi-Power it just doesn't work at all, because the support hand thumb will tend to kick the slide stop on.
What I do with the Hi-Power is I keep everything else in the same position, and curl my thumb around the trigger guard (I have huge hands, and thumbs like Hendrix. I can just about fret the high E string on a strat' with my thumb). This works for revolvers as well; and pretty much for the rest of my guns, with some slight variations.
With the minimal change, I don't think that having two different grips for my guns is going to throw me off so much.
