I started a thread about the 8500 vs the 9815 over at soundillusions. The general opinion was that for the best SQ, go with Alpine units. People who owned both posted, and although the 8500 is a little more snazy looking, the Alpine wins in SQ. One downside a lot of people had is that the 8500 is slow in reading MP3 cds. After reading replies, and doing a search(as the topic had been discussed many times before)I went with the Alpine 9815.
I havn't yet installed it(hopefully tomorrow or wed)So i can't write a personal opinion yet. They both retail for around $500, though if you expect to spend under $350 and had the 8500 in mind, can I assume you are getting these without the retail markup?