Both good choices.

Is your dealer friend a CI or authorized? Make sure he is so you can get the SW.

Both do RF and are great remotes. The 900 is a step up, obviously, but chances are the 850 would be fine, depending on what you want to do. Both are PC programmable.

However, "can't sense that my tv is already on" refers to variable programming. The 850 most likely has discretes for on and off, but you seem to desire variable programming, which the 850 will not give you. I can't remember if the 900 does. You may have to go up to the MX-950 for variable programming.