The problem is we can't possibly ever know which of those two options is correct, and there is nothing to sway us one way or the other, so to have the answer we would literally have to be in Cooper's mind, which obviously we can't do. So I don't see this particular line of inquiry to be helpful.
For me, the only aspect of Cooper's parachuting acumen that we can have reasonable confidence in knowing is the belief that he was NOT a recreational skydiver of any sort. We know how the skydiver copycats behaved and we know how the non-skydiver copycats behaved. There is little doubt that his behavior falls in line with the latter category.
On a sliding scale of "parachuting know-how" among all of the parajackers, Cooper seems to fall in the middle. Yet the main reasons I place him in the middle of the road, aside from Tina saying he seemed comfortable putting it on, really come from one source: Tosaw.
He is our ONLY source for Cooper complaining about D-rings and him looking at packing cards, which are the two things that really elevate him above the McNally's and Fisher's of the world. As I've said numerous times, I would lean toward Tosaw getting that from Tina back when her memory was closer to the event than it certainly is now. Additionally, Tosaw was of the belief that Cooper was foolish and got himself killed. It doesn't benefit the narrative of his book to give Cooper enough parachuting knowledge to know what D-rings were and to know what packing cards were. So I would lean toward him not making that up. The packing cards especially would be a bizarre detail to invent for Tosaw.
However, there have to be some slight embellishments or artistic licenses found within Tosaw's narrative. That's just the reality you face when writing a vivid narrative like he did. So might him bitching about the D-rings be one of those?
Regardless, as I said, the only thing we can be reasonably confident in given the case evidence and comparative evidence with the other parajackers is that Cooper would have gone about things differently if he was a rec skydiver.