Drive one to see for yourself! I can only speak for the 6 cylinder, 188 hp diesel, but I hear the same about the 4 cylinder. Acceleration, power, and handling are quite good and I think ours is aerodynamically worse and heavier than the Class Bs. We tow a Chevy Sonic (~2700#s) when we need to and can't even tell its back there from a performance point of view. Ours is so easy to setup & disconnect and maneuver, we usually just take the RV to places while we are camping....even if we towed. Then you have all your stuff with you. In our case, it also makes it easier to take our dachshunds. Given a choice of the Sprinter vs a Ford or Chevy engine and chassis, I'll take the Sprinter every time....and I'm a lifelong GM addict.
Norman & Janet with Minnie the Weiner Dog
2005 SunnyBrook 38 BWQS 5th Wheel (stationary in FL for snowbirding)