A lot depends upon the questions asked above. If you're gonna travel a lot, probably a mh is the better way to go.
What in the world do you need a roll around tool chest for? I do carry a good assortment of tools with me, but all can easily fit into a small chest that I can pick up. It's a common error for people to want to take much more with them than is really necessary. Most items, when needed, can be purchased.
Another food for thought is the type of vehicle you want to drive when not in your rv. Most times, driving a 1-ton dually around in a crowded city can be a little uncomfortable.
There have been many posts regarding mh v.s. 5er. Do a search and I'm sure you'll find most of your questions answered already.
Good luck in your decision.
Ron