You would be upgrading to v14 at this stage (or at least have access to it). SSS (how light goes through wax) has been added and there are render improvements. Also, some nice new touches here and there.....like bones turning blue when your on the same frame as they're keyframes. Also, you'll have the latest model format and won't have any incompatibility issues as you may have had with v12.
I'd say it's worth it and Martin would appreciate the extra few bob to mend his shoes.