I put quick connects on all the machines I've restored, rebuilt or shopped. Then those machines go to the Northwest Pinball and Arcade Show for an entire weekend of play (many of them have been back multiple years now).

I've only had one incident where a quick connect has come loose. I tightened the contact and re-inserted it onto the coil lug and it's never come off since.

I've also had one coil burn up during the show (same machine I think) and replacing that coil on the show floor was super easy.

I suck at soldering at a machine when the playfield is vertical. On a bench (or table) I can solder just fine.