I've got HS 11s on my '98 Cannondale T1000 and have been really reliable and still provide great power (with the regular black pads). But because of their age I don't want to be stuck in the middle of nowhere if a line bursts, so I'm looking at replacing them with cable brakes soon. In the spring I put on a taller handlebar stem and I had to replace the front line with a longer one. It was a fairly messy job, but I did it and everything works fine; no way I'd do that on the road! Not really complicated but tedious. I'd recommend before you buy that you know where to find replacement parts and a mechanic whose familiar with them.
Also they've only been adjusted once in the 12 years I've had the bike, and I like that the pads are so easy to replace.