Your boss will regret the Sprinter if they are as fragile as we tend to see, sounds like your Transit was regularly overloaded and booted. So the Sprinter won't last anywhere near as long.
I had a LWB Talbot Express works van, I left for a while but when I came back to work I got my old van back, shame the driver who had been using it while I had been away thrashed the living crap out of it as it was noticebly slower and the pickup was sluggish and the clutch was well high. Different driving styles and this persons lack of gear changing stuffed the van. The driver denied he miss-treated the van...yeah right

I saw him driving other vans the same way as a pedestrian and as a passenger plus he was allowed to take the van home so he was thrashing the hell out of it doing boot sales and the like all weekend. All it needs is a little mis-use and things like this will crop up. It took several oil changes and a new clutch plus a full injector bleed (about 5 times) plus I think a couple of injectors too...oh and the gear change linkage needed to be rebuilt as all the spring pins had been lost. All this work to get the van back to how it should have been when I got back to work....crazy!
This driver also wired in a radio using Blue Tack to hold the connections in place...seriously! This was a different van that I had to use and the damned radio caught fire I burnt my fingers ripping it out with red hot wires and loads of smoke so this tells you something of this persons attention to sensible things.