the only thing Id say is, be prepared for a fair bit of rebuilding, replacing, maintenance or just cleaning if you go for a used commercial.
Now if you are a person who takes great delight in doing that sort of stuff, youre in heaven. If not, youll drive yourself, friends and family crazy!
Its a bit like an article on classic cars in our local motoring magazine Open Road. It says something like, make sure your family is on side before you start, and be prepared for the fact that everything you buy will have problems.