Christoph,
As I already said in another thread, our company utilizes VDI in many remote sites. We have single users in home offices across both Cable Internet and DSL connections and have very little trouble with them. Some of our remote sites are 100-300ms in average latency. Where we have multiple users in a remote site like the office I was asking about in the other thread, we have problems, but remote sites with 1 user seem to work just fine with very few problems. Since I didn't know about tweaking RDP with GPO, we haven't done anything like that, so if you already have, you might have even better luck than we have.