I think the technology already has advanced to the point of excellent reliability. Literally almost every diesel engine comes with a DPF now. There are going to be repairs, no different than any type of mechanical / electronic item. The only reason I'd consider deleting is simply if the cost to repair factory emissions was too high. I also don't think there's much danger in performing an "illegal" delete. Be it a pickup truck or tractor, the dealer wouldn't file charges against you, they'd simply say they couldn't take your vehicle or tractor in trade because it didn't meet federal emissions standards, and that would be that. Most private sales would be fine since prospective buyers, for the most part, will look at this as a benefit rather than a demerit.