I am using a 15 year old amp and have friends with 30+ year old amps. I would not think twice about using the homebrew amp if you can make them work! In most cases the sub is the "slowest" of the speakers. The larger cone has more mass, so it is harder to start and stop. An amp with a high damping factor and a lot of current reserve should help to bring synergy to your system.
Chris
Chris