Well, when you compare maintenance with a MH to a truck and a TT, its important that you compare 'apples to apples'.
When you step up from a TT and truck to a MH, you frequently step up a bit in terms of components, amenities, etc. Not really fair to compare the maintenance on a high $$ diesel pusher MH with all kinds of 'bells and whistles', to maintenance costs on a fairly simple TT and gasser truck. Of course the MH is going to have higher costs in that case.
If you wanted to keep maintenance costs from going up significantly when trading up, you should have got a more simple gasser MH.
This is one of the reasons when we moved up from a truck and TT to a MH almost 2 years ago, that we avoided the high $$ DPs. We went with a more simple gasser MH built on the F53 chassis. It has same engine our truck had - Ford V10. The components on the coach are very similar too - refrigerator, Air conditioners, furnace, slideouts, awning, gas stove and oven, etc.
So far for us, maintenance expenses with the MH really has not been terribly different than it was with the truck and TT we had before. Now, the extra cost of all the add-ons, modifications, and setting up a 'toad' to tow behind the MH....THAT is where the 'love/hate' thing has been for us, haha. :)