IF the patina is the factory original paint, then yes leave it, especially over doing some cheapy mess paint job.
I say there is way more value in a good quality paint job than patina, as long as you have good photos to prove what was and is under the new paint and the new paint is good quality and done correctly. The reason there is more value is because a good paint job is valued in the $5000 up range. Patina is fine if the rust is put at bay and its not meant to be driven and parked in a museum. Most people that see a patina job think its just a cheap pile of junk, and look down on who ever the driver is. If patina was as cool as some folks think it is, then the new cars shipped to the dealer would be sanded to primer spotted messes and there would be no reason for body shops to fix all the fender benders.
