I was told by the dealer that the paint process they started using in 2014 was the same 7-step process they use on their $100K+ cars. Additionally, they pointed out that there is a "wax-based" coating inside the body panels and that it will drip (especially on hot days) through the little weep holes. The undercoating on mine is the most robust I've ever seen on any vehicle.
A salesman told me that the entire van is dipped into some sort of primer solution twice. He attended some sort of factory tour. He also commented that the question "What is being done to improve rust resistance" was the number one topic of discussion. I'm guessing that Mercedes is doing "something" to improve the Sprinter.
When I inquired about dealer package rustproofing for the Sprinter, I was told that no one will warranty it because of the rust reputation.
I can only hope that there is some truth to the stated process improvements.
Looking underneath the Sprinter, Transit and Promaster, the Sprinter has the most undercoating applied.
The Transit and Promaster both lack body cavity wax.
Only the Sprinter has front wheel splash shields.
None of these vans have rear wheelhousing splash shields, and all have exposed wheeltub pinch welds facing towards the tire. Only the Promaster has an appreciable built-in deflector to keep the bulk of the debris from hitting the edge of the joint, but that same deflector will act as a debris shelf.
I chose Tenorite Grey Metallic for my 2016 144 cargo. I like the color, it looks nice, but on both the driver and pass doors there's an imperfection. It seems like a small, congealed glob of paint or foreign matter. Most would never see it or know that it's there, but I'm a detail oriented owner and found it immediately. This has never happened on any vehicle I've ever owned. Also, the oily, waxy stuff MB uses to spray the underside and wherever else, a lot of it ended up on my paint and trim. The dealer did a **** job of detailing the van, so I did and got rid of 99% of it. The dealer will take care of the paint imperfections but the shop they use can't guarantee that it'll turn out perfectly. MB may say they use the same process on our vans as they do their 100K sedans, but I'm skeptical. I'm happy with the color, but something tells me the van division and van owners are treated in a much more industrial fashion as opposed to the build line spitting out 500SL models...
The same dealer service manager told me that it takes them hours to detail a Sprinter for delivery, due to the wax overspray on the finish.
My 2008 also had a blob of something in the paint on the sliding door. The spot was oval shaped, about 3/8" x 1/4". I left it alone.
Getting the repair to blend in will be near impossible.
With metallic paint, they will have to spray the entire door with the base coat and then reapply clear coat. You will have tape line edges around things like rubber and door handles and trim- these items are not normally removed. Clearcoat can't be blended in, they have to take it to the next panel, seam or body line that can be taped off.
The *entire* van will have to be masked off to prevent overspray.
The door will then have a uniform appearance, but depending on the light, the door will most likely stand out against adjacent panels due to a difference in how the metallic particles lay down.
Blending in the solid single stage colors is much easier.
Not knowing how noticeable your paint defects are, I'd say to leave them alone. I am doubtful that the repair will be better or worthwhile if the defect is purely cosmetic.
It is possible that a paintless dent repair person could approach it differently and perform a very nice spot blend job. I'd consider that well before doing a traditional body repair.