With a budget of 50k for a 34 ft +, you are, of course, looking at a used unit. Dependability of any used vehicle always raises questions in my mind; you just never know how many problems may lurk. Year for year, a gas motorhome will cost less to purchase and maintain than a DP.
Not hard for me to place myself in your shoes, as we bought our first rig and went full time this year. We bought a 2005 Itasca 33V with a workhorse chassis. It was below you budget (and ours), but we knew ther would be more costs as we fixed it up to our liking and such. Fulltiming ( and lacking a driveway, lacking extensive on board tools, and lacking both engine and rv expertise) we knew we'd have to pay to have professional work on our unit, though these forums have helped us fix some things on our own. We have been pleased with the reliability so far. We shopped on line and in person in Florida, ended up finding ours in TX. We tried to look at mostly units with good reputations including Tiffin, Winnebago/Itasca, Holiday Rambler. We wanted a good price so we would not take too bad of beating if we sell or trade up.
I read an e book by Bill Myers on buying used Motorhomes and found it helpful.