actually, the scottish rebels are not that broke.

they often pump out clansmen and can even build up pictish cav on their own.

I would say take it and keep it revolting to train your troops.

keep the province as clansmen are very useful.

bribing welsh longbows mean that you can knock out the clansmen easily esp. if they are already hardened by combat in france. (hmm sounds historical in the tactics against scottish rebels even though I actually succeed in wiping out the French entirely)