I've been using my R-1500 for a few weeks now. Compared to my WinRadio G303E, it isn't quite as sensitive, but very close (it is alot better than I expected). I primarily use it for listening to utility and HF aviation. I have the UT-106 DSP module, and with it, it does a better job with HF digital modes than the G303.
It's scanning ability is great. I tend to use my G303 for finding stations, and the R-1500 for scanning/listening to them. I have to say, I've been quite impressed with the R-1500. It performs much better than I expected given it's frequency range. I haven't done any real comparisons in UHF/VHF, but it is at least on par with my BC898T and probably better.
I've yet to use it above 900MHz, since I don't have a suitable antenna, but hopefully I'll find the time to build an L/S band antenna this summer.
Well, that went a bit outside the scope of your question, so I'll leave it at that. If you have any more questions, I'll do my best to answer them.
Regards,
Carl