I've been using DomainDirect (which is now Hover) for about 10 years and never had a problem with them. I did have one minor (login issue) hiccup with my main domain right after the Hover transition and had to call their tech support. After a very short wait, I got a guy that both knew what he was doing, and spoke quite clearly. The issue was resolved moments later.
They're not the cheapest (@ $15 a year), but I think well worth it for the clean easy to navigate and use configuration system they have. Registrar chances are usually done very seldom, and it a panic ... so you don't want to be screwed (banners, popups, more confusion) with while it happening...and they don't. I tend to appreciate that kind of thing.