I used water cooling twice, once with my ST10, once with the ST9, and whilst it does make an appreciable change to the cooling head room, I don't think its worth the hassle of having a bucket next to the mount, around all the power/data leads... Seemed a little dangerous. In an observatory where everything can be neatly organised, I dare say its not too scary, but out in the back yard its disconcerting to say the least...
-53c on the STX is a good result for sure, and 80c would definitely eliminate a bit of noise!!