Thanks for the explanation. I've only bought Stardock exclusive games (GalCiv and Sins of a Solar Empire), one or two indie games, and Demigod. The behind-the-scenes installation is indeed a little odd, and it must be frustrating to have to download large files again and again!
I have to admit it's been a while since I last used Impulse. When I had to reinstall Windows again on my main computer, I realised I actually hadn't played any of the games I had on there for a quite some time and, more damningly, didn't feel like picking them up again either. I know it's blasphemy, but there's something utterly soulles about GalCiv (the original, the sequel, the expansions--I have them all, sadly) and something mind-numbingly dull about Sins of a Solar Empire (and I really like the concept!), that I just didn't see the need to reinstall them. Demigod was fun, but I'm not missing it.
However, I did reinstall Steam. The client isn't fantastic, but the games are good, both Valve exclusives and otherwise. I don't think Impulse stands a chance in the long run.