Repower old sub - like a Rel Storm, Stradia or Britannia or buy a new modern sub?

I've been trying to fix the amp on my Rel Britannia - I've replaced the relay and a few capacitors hoping to fix the problem but I'm likely over my head and my problems persist.
I was thinking of buying a new plate amp from Hypex or a chepaer amp from Dayton but I'm also wondering if instead I should cut my loses and get a more modern sub. The smaller footprint of a new Rel T7X would be nice but I can't help think the massive 100+ lb Britannia is a much better box. What do you guys think? What would you do?
 
I added a set of speaker terminals to the Rel plate and run a miniDSP flex to a crown amp. Might upgrade the amp at some point but the old crown works well enough for the volumes I play at.
That's actually a good idea. Saves the extra effort of dealing with the amp plate cut out. Dies the amp have to be subwoofer amp or any amp with correct power rating and impedence will do?