You do not have BMW warranty with Dinan parts or software. Most dealers put Dinan mods in the same basket with any other aftermarket mods. I would much rather just re-install my original software thru the ESS E-Flash when I go in to the dealer and have my factory warranty than deal with Dinan VS BMW. I have gone in several times for service and warranty work and I always just reflash to my original stock file.
Dinan also has no remote tuning options so you have to take the car to a Dinan dealer whenever you need a change, update or reflash. For me this alone is a deal breaker. There is also far less in options with Dinan software like Valet mode, Cold start delete etc... That being said I would trust my car with Dinan if there was not a better option available but there is.
Performance = ESS tune
Options= ESS tune
Ease of installation= ESS tune
Warranty= ESS tune