I started with SmartHome in the pre-insteon days. I have a pair of dimmers (Which only respond to the old dim/bright commands, not the extended ones - but I never dim them), and a three-way relay setup for the fluorescent fixtures in my family room.
The rest of my SmartHome switches are all newer, and I decided to go with Insteon for those. I was replacing the original X10 (non-SoftStart) wall switches, which seemed to have a mind of their own sometimes. I also wanted to switch my outdoor lights (four switches) to CFLs, as well as (eventually) two indoor fixtures. I needed relay switches for that.
Smarthome's latest X10-only switches weren't out yet at the time, but the previous edition were. At the time, I felt going with Insteon was a better investment, since (and this was a few years ago already) I didn't know how long I'd stick with X10, and the Insteon switches gave me the ability to convert over to Insteon without having to replace those switches again. I now have 6 Insteon switches in my setup. I've been happy with their reliability, and the customer service I got from SmartHome (two of my pre-Insteon switches failed within the 2-year warranty period, and they replaced them with Insteon switches at no additional cost).
I've bought other stuff from them, and I've always been very satisfied.