Overall RJ's do not provide hub bypass flying. In fact, like KC said they have replaced full sized airliners with the 50 seaters. If you are a fun of long ATC delays then you must love RJ's. A majority of our problem with the ATC delays results from many of these airplanes clogging the scopes of ATC. In many markets the mainline carriers have had to add 4 to 5 RJ's to cover what used to be flown with 3 737's or 319/320 airplanes. The airlines tout this as giving the consumer a choice in departure times but when it comes at the expense of an ontime operation because the system can not absorb all those flights, then you are really doing them a disservice. DL,UA,AA,CO,NW and US need to scrap the RJ plan, put a reduced number of mainline flights into the markets and crap can those stinking RJ's. Also, the RJ's are often weight restricted on an average 1 hour segment. This is UFB! These airplanes are doing nothing to increase the passenger enjoyment. If you really need a dollar beer then go to a happy hour. If you want reliable transportation then look for something other than an RJ.
Also the CASM to fly a 50 seat jet is astronomical. Just look at the cluster duck of an operation that was Independence Air. Charging $49 buck to fly the RJ when it was about 4 times that in cost to themselves. They blew threw 250million in about 9 months. Your friends at Expressjet are doing the same. While still clinging to the CAL dollars they are losing their collective arses in the point to point "we have a grand plan to go it alone" operation.