We made the change 2 years ago. We had a 30' 5er with 2 slides, and now we have a 29' B+ with 3 slides. On the minus side of the class C, since part of the 29' is cabin area, the living area is smaller than our 5er. We find the living room clearly large enough for the 2 of us + on 50lb dog. The bedroom is smaller and the shower is smaller (we had a tub/shower in our 5er). The biggest minus is the lack of counter space in the kitchen. On the plus side, it is much easier to set up and tear down, ie, no truck to engage or disengage. The same is true for any require service, just hop in and drive away.
hope this helps