I have not ruled out a 16 as there is a very nice one at Cabelas in the price range I'm looking at. However that featherweight 20 is really 6 lbs. I watched the guy put it on the scale and it was pretty much what put me over the edge. My veloce is 6lbs 13 oz and and do feel it's weight after a long day. That was part of what pushed me to look for a lightweight classic american double.
Now my biggest concern is the chambers. The featherweight 20 is sure to have 2 1/2" chambers. Do the RTS 2 1/2" 7/8 oz 7.5 shot do well on grouse? I would go with the 8 shot for woodcock.
Also, are the RTS hulls reloadable? I have a MEC 600 jr 20 ga reloader and would love to do my own shells for the elsie.