I do not regret my Brompton purchase. I agree that you do pay a premium for many aspects of the setup. I elected to go singlespeed to save weight and money and keep things simple, and figured if I decided to later I could always do an aftermarket SA setup. For what it's worth my one way commute is 28 miles. I've been doing it 3-4 times a week on the weeks I don't drive.

I still consider doing a Swift build from time to time and maybe I eventually will, but my custom Brompton had every option I wanted right out of the box and it just works. The tinkerer in me still isn't quite at peace with that but there are other bikes to mess with.