Plus: my 15 yr old brompton is riding well Minus: only the frame, brake calipers and rear hub remain of the original (some bits replaced for weight or comfort but mostly wore out) Plus again: you can get any spares you need to keep riding

The red Brompton on my wall has the original frame and stem. Everything else replaced. It has been rebuilt as a Brompton P-line clone with a 5-gear cassette, 218% gear range vs P-line 164% and a weight equal to P-line.