MY department issues Glock 31's and I dont mind them. I usually carry a 1911 or a Glock 21SF (modified) off duty. I do like glocks because they are a good tool for what they were intended for.....they just need a better grip angle. I use to carry a standard Glock 21 off duty because I prefer 45. I finally got a chance to try out a Glock 21 SF and I liked it so much that I bought one. Then I sent it off for a grip reduction, mainly to remove what was left of the palm swell on the lower part of the back strap. I love my Glock now!
As far as transitioning between duty and off duty guns, I dont have a problem. When I train with my firearms, I use a Threat Focused Shooting method, which requires little use of sights. This helps due to the fact that the shooting method works with just about any pistol.
Most of your shootings involve low light, at close range, and most officers dont recall using their sights. I have had to draw my weapon several times while the adrenaline was pumping and I never remember seeing my sights. I just remember seeing the target and the silhouette of my glock.
I guess I am biased toward Glocks because I have used them for 10 years so far and they have never let me down, but that doesnt mean that there wont be a day. I am a big fan of the 1911 and I own two very nice ones, but they are not tolerant to the elements like my Glocks.
I like the XDs as well. I just dont like the triggers and the fact that they cant be fully disassembled without the use of a punch and hammer.
I say carry what works for you. Train with your duty weapon and get a feel for it.