I have eyeballed the R8 and TRR8 for a while now. About six months ago I saw a TRR8 at the LGS. At $750 I couldn't say no.
I chose the TRR8 over the R8 because the rails are removable. I don't plan on mounting any lights, lasers, or optics on it, so I just leave the rails off.
She shoots like a dream. .38s are super light shooting and .357s are pretty tame too thanks to it being an N frame. The trigger is super smooth and has a clean break. The grip is really nice too. I also like how easy the brass bead front sight is to see.
I've had no problems with her. She always gets lots of looks at the range. Overall, I'm glad I bought it and she seems to follow me to every range outing. I would highly recommend one. The only con I can think of is the price.
These were developed in response to a problem NYPD swat guys were having. When using a shield, their semi autos were malfunctioning because of the slide hitting the shield after firing. They told S&W they needed a high capacity revolver with the ability to mount lights and lasers. S&W then came up with the R8 and TRR8.