I think its more of a head game for some, than its really an issue of grip angle.
If you track the sights, its a non issue. If you point shoot, and have spent any quality time with any of them, its a quick readjustment, and usually accomplished within the first mag, or a few presentations.
I shoot all manner of things, back and forth, and have had no issues switching. A couple of quick draw and presents, and Im usually right on track.
The only things that might take longer to adapt to, are things that are new to you, that you dont have the experience with yet to have your brain register them. With the majority of things all being pretty close grip angle wise anyway, its really not a big deal as far as grip, as it is with controls and MOA's.