Thanks for the tip on the Riordan Turbo resonator. We've had the resonator fail, alternator ($1,100 for part alone), leaking fuel fittings, failed idler pulleys (2),transmission leak, two failed A/C/heat blower switches, brake pad warning sensor, EGR valve, even the antenna fell off ($200 for part). This vehicle is parked under cover each night, and has 54,000 miles. I realize the OP wasn't looking for opinions on Sprinters, but I just cringe thinking someone is considering buying another one. Here in the Atlanta area, biggest problem is dealers. They are mostly concerned with getting you a manicure, or a massage, or signing you up for yoga or hitting balls on their driving range, or tasting their gourmet coffee-anything but fixing your vehicle. You can only talk to your service advisor at a scheduled appointment, and don't even think of talking to a technician! OK, thru ranting. I predict that three years from now virtually every class B and B plus that's on a Sprinter chassis now will be on a Transit chassis, and you'll be able to get them worked on at every town in America.
My daughter has a mobile grooming van built on a 2006 Sprinter 2500. It is similar to an RV in that it has fresh water tank, gray water tank, 2500 watt invertor, shore batteries (six 6 volt), two water pumps, plumbing, electrical etc. While we have it mostly sorted out, it has been the most unreliable and expensive vehicle to service that I have ever owned. I just purchased a 2016 Pleasure Way Lexor TS. I did not consider any class B built on a Sprinter chassis. It sounds like you are thinking of buying a new class B? If you don't like the RAM Promaster, why not wait until a class B you like is built on a Ford Transit? For every other type of conversion, they are rapidly overtaking Mercedes in sales. I believe it would prove to be considerably more trouble free, and far easier and less expensive to maintain. JMHO.
I cut a rubber backed bath mat to the dimensions of the shower pan (20 x 14.5) in my Lexor TS. The mat is always on the shower floor, keeping the pan clean. If I take a shower, the mat is placed just outside the bath door, where it is the first thing stepped on getting out of the shower. Am never stepping on shower floor except when taking a shower, and I wipe the floor along with anything else
remaining wet. Floor stays shiny clean. Looked at hard products (like teak grate), but thought they would scratch floor, and wouldn't serve as bath mat to step on getting out of shower.