I have owned 2 Sprinter diesels and now have a Promaster gasser. I think the Sprinters were better built overall but the diesel engines were very expensive to maintain. I do love the driving experience of the Promaster because of the front wheel drive and tight turning radius. Sprinters seem ponderous while Promasters seem more agile on the road.
I bought that van as an empty box and did that build in about 3 weeks then lived out of it for about 5 months in-between houses. after i got my new house I still spent about 50% of my time in the van on the road! Looking to continue that asap!!!