I think you pretty much nailed the pros (faster mag changes and they look nice). The only con I could think of is the extra length added to the grip if you carry the gun.
You can install these yourself - heck, I installed a Smith and Alexander one on my 1911 without any problems at all and I'm definitely not a gunsmith by any means (if I haven't taken down a 1911 in awhile it can be a pain for me to put back!). A professional gunsmith can do blending to make it look seamless, but in my case the S&A fit very well to my old S&W 1911.