Regarding engine issues, there's always going to be the one-offs. Someone will have a piston grenade itself at 5k miles while idling. Someone will have four fuel injectors in a row fail time and again. You get the idea.
The only thing that comes to mind, and its only been reported by a couple members here, is some issues with the flex plate cracking on the gas engine and automatic transmission combo. But realize, folks generally come to a forum and scream when there's a problem. You don't hear about the multitudes of folks that are driving along just fine.
The other small issues seemed to be mostly with the 2014 first year models. I remember a few folks having problems with water leaks from the top front marker lights. A few reports of mis-aligned rear doors (one currently being discussed). Overall though, nothing sticks out to me.
Regarding the engine side of things again, the V6 is their 3.6l Pentastar. Its basically the same engine that's been used in the Chrysler minivans for years. Some may say its overworked in a 9500gvw van, but that's what gearing is for. It should do just fine. It has been refined for many years, and has the advantage of being easily serviced because of the extensive knowledge of that engine. As for the diesel, it is a new creature to the North American shores, and it has gone through some teething problems in the early years. But it is based off a very solid commercial duty engine and transmission. The same combo is available in Mitsubishi Fuso trucks with nearly a 20,000# gvw, so I think it will survive just fine in a PM. Service could be a bit trickier though.
Oh and we have a 2008 Mini Cooper Clubman S. Yeah, it was serviced for the timing chain stuff, but I don't see that has affected its resale value at all. (we have just put it up for sale; fun car, but we're going electric and replaced it with a BMW i3).