For a hunting gun I much prefer a straight grip as I find them much more comfortable to carry--especially for long periods of time. I recently sold a pistol gripped 20-ga. Sterlingworth because I found it didn't carry as well as my straight gripped guns.
For a bird gun that sees alot more targets than it sees time hunting I can go either way, but I prefer the aesthetics of those that are straight gripped. Those that claim you have more control with pistol gripped guns will get no argument from me, however.
If you do go with a straight grip I'm confident you'll like the final result much more if you have the tangs bent up, because if you don't the result is a funky looking gun. Toby Leeds bent the tangs up on my custom 20-ga. Sterlingworth Special when he converted it to a straight grip and restocked it.
