I finally saw and held the MX-850 and MX-900 units at the local Tweeter store. I was not able to test the units but I can say this: The MX-900 was way more comfortable and a lot easier to read the LCD than on the MX-850.

I did not buy the unit yet. Tweeter charges the MSRP of $449.99. Buying the MX-900 at this price is like paying the full sticker price on a car without negotiating with the dealer.

Many reputable dealers will be selling the MX-900 at a reasonable discount price very soon. The MX-850 is already selling at less than half of its MSRP right now. I realize that it is very tempting to pay $225 now at eBay for the MX-900, but, is that a wise thing to do? They may not offer a warrantee. We all just have to be patient.