In one of my bands, I use a Duo-Capture connected to my iPad on my keyboard rig for live gigs. I mainly use it to send MIDI back and forth between my iPad and keyboards, but occasionally for other purposes as well. In another band, I use it to play high-quality instrument samples via WX5 wind controller through my iPad. It is rock solid and sounds great. I tried another interface but went back to the Roland for its simplicity and reliability. I've also used it on my DAW when I was having issues with my main interface, and I was very impressed. Low latency and good sound. I also appreciate the fact that it can run on batteries, although I've found they don't last long.
At one time I also had a Quad-Capture, which was also a high-quality unit. I thought I would use it with my laptop for live gigs, but then I started veering towards the iPad. Unfortunately, the Quad-Capture was not compatible with iPad, so I wound up selling it. It was an excellent interface, though.