So, for those who are interested, US has now completed outfitting all of the US Express ERJ 170 and 175 models with First Class, as of 10/18 for the E175, and 10/31 for the E170. There are a total of 38 E175s, and 20 E170s.Now they are going to begin CR9 and CR7 modifications, or already have started the cabin mods. Here's a bit of "trivia", I guess you could call it..
The percentage of FC-equipped RJs among the majors, broken down by airline, includes all Express carriers:
American Eagle: 47 FC equipped RJs out of 284, Total: 16.5%
United Express: 132 FC equipped RJs out of 292, Total: 45.2%.
United Express + Continental Express, Total: 25.8%
Delta Connection: 223 FC equipped RJs out of 664, Total: 33.5%
US Airways: 110 FC equipped RJs out of 298, Total: 36.9% (When complete)
US Airways: 58 FC equipped RJs out of 298, Total: 19.46 (ERJ only, as of 11/2/2011)
(These are only estimations, and the UAX+COEX numbers are slightly out of date, but I think they are still close to the actual numbers, as CO had no First/Business on any of their Express flights)