I'm pretty sure the 2116 doesn't have an extender. (I even checked the extender folder in the JP1 group to see whether someone wrote one and I missed the announcement).

I don't have either an 8910 or a 2116. I have a borrowed 8811 at the moment. I think it is much better than I believe an 8910 or 2116 would be (based on the pictures and descriptions I've seen). I personally think the LCD (which the 8811 lacks) is worth zero (or less) so that eliminates (for me) the significant factor that makes many prefer the 8910 or 2116.

I believe the 2116 has the non slip coating similar to the 15-1994. That is a significant advantage. I wish the 8811 had it. But it doesn't overwhelm the other factors.

I believe the 2116 has too few total bottons for a remote control fanatic. But I haven't done a detailed comparison of which buttons are different between which models.

I believe the 8910 has WAV file upgrade. JP1 upgrade is simpler and better than WAV, but if you don't want to build or buy a JP1 cable (or your computer doesn't have a printer port), WAV file upgrade is better than nothing. (The 2116 and 8811 don't support WAV files).

The 8811 has the best extender (so if you want to extremely customize the remote's behavior it is the best choice).

I think the 8811 has the best key layout of the three (though I think the cluster of keys at the bottom of the 8811 are too uniform and too close together). I want to use a remote while looking at the TV and NOT looking at the remote. None of these three come close to a 7800 in making that easy, but the 8811 comes closer than the other two do.