So, the temperatures of the newer CPUs are, across the boar, lower than they were when the 5Ks first started coming out. And the fans could handle it back then (although my fan on an original 5k sometimes goes to 3.300RPM when 2700 is kinda meant to be the max...). Your fan will definitely run faster with the i7, but it's not that huge a difference.
The i5 is still a lot faster than your mini and Air though. If I were to wager a guess, I'd say you'd experience somewhere between 5 and 20% speed ups between your tasks. That's compilation speed at the high end of that estimate, and render speeds on the low end. Adobe's apps generally don't make the most of all the cores you give them so your main speedup there would be from the increased clocks, as the hyper threaded cores tend to sit idle a lot of the time with Adobe apps.