Ed Brown pioneered the Bobtail grip, reportedly for the primary purpose of lessening "printing" of the pistol grip as it was draped by clothing, e.g., jackets and outside the belt shirts. But then some people learned to prefer it for the feel of this shape -- and I do too (I have a Dan Wesson VBob Commander). This is the most comfortable grip for me. If I grip it very strongly, I notice the muzzle seems to rise just a bit, but in practical terms there is no difference (for me) in the point of impact/point of aim between the bobbed and a regular grip with a flat MSH. I don't have any experience with the 1911 rounded grip, but I suspect it has the same virtues as the Ed Brown Bobtail design.
There are other variables to consider in a grip on a 1911 (other than shape, e.g., bobtail, rounded, standard 1911A1 flat, or standard 1911 arched). Things like thickness of the grip panels (slim or regular) and their finish (checkered or smooth, etc.); finish treatment on the MSH (checkered, fluted, smooth, etc.); distance to the trigger (long, medium, and short). It comes down to personal preference. My preference, for a Commander model, is the Ed Brown style Bobtail with aggressively checkered VZ thin G-10 grips and a long trigger -- but your opinions may vary! (Added: and I have a EVO-KC9-GEN4 on order).
All of my carry commanders are now bobtail. Both DW, Classic Commander and primary is a Guardian. Love them both, they fit very natural in my hands and I have XL hands.
Find a friend with one and go shoot it if you can.
ok, sold to the man with the pointy head. thank you so much. lots of great replies! i will get with george and figure out the finance part. probably won't be able to order until june, i plan to go ahead with the kc lw bobtail. thanks again. best, james