lopakamac - Your choices seem to boil down to personal preference. The exterior length (RoadTrek 210 = 21'-11", B+ 213 = 21'-11", B+ 235S = 22'-7") is only 8" difference, so handling will not be different. The interior space is very noticeable between the B+'s and the RoadTrek. I favor the Chevy chassis for both. Interior headroom was a big factor for us, I am 6'-4". As to the possible leak, it is always possible when you open up an entire sidewall. I park differently when rain is expected. It has not been a problem for us and the extra interior space is really noticed when parked for several days. The only maintenance we have had has been done at places like "House of Muffler" - oil changes, install new shocks, rotate tires. For chassis work, look for the GM medium duty truck sales and service locations.
lenc - Haven't heard from you since you got your new rig. Any comments?