Ok, first "learnt on" would be a Singer 1911A1.
Yes, arched mainsprings are a feature of my subsequent life.
First owned was a Series 80 Officer's which was high and left until I got an arched m/s housing <g> <sigh>
Ok, in spirit of thread, first I bought that I was disappointed in would be a stainless AMT hardballer, which wound up traded for a sweet M1903A3--and both I and the deal thought we made out like bandits.