I think James Clay gave you a good objective comparison and you have lots of useful opinions. But I think you're looking for data that no one has...a direct comparison of lap times between the 2 coilovers? I've never seen that anywhere for any model.
Not sure what else we can provide on the forum. Recommend you do some old fashioned dialing. You'll probably get somewhere a lot faster.
On the buyer's remorse thing, I'd rather overspend once than underspend and then spend again. I've been down that road a couple of times and learned my lesson. I think moreso with BMWs and even more often with Ms that parts are marketed as upgrades but they actually turn out to be inferior. You really do need to spend money on parts to get something truly better.
2015 F34 328iX GT Glacier Silver
2011 E90 M3 Monte Carlo Blue
2004 E46 M3 Imola Red