DT200 motors especially parts are not as abundant as YFS motors and parts though. Yes though this would be ideal for liquid cooling though you need a lot more than just the head as jahrastapark stated, and it will add up quick. Search how easily parts are found for them.....your best bet would be find a complete DT200 motor and swap though this will not be a cheap endeavor.
There has been a few threads discussing this product here before (use search) but I have not seen a review. I would be interested however as the head is really where the YFS motor is hottest. I don't however see heat being an issue unless you have made major motor modification, though it might improve reliability slightly by de-creasing running temps over long-term. I don't see what it would hurt, yet is just one more thing to go wrong. Who knows though, IMO Just get your head modded to adjust squish band without the water cooled feature, what is it like 60 dollars from KOR?
In the link you posted though the design is improved over the ones I've seen on ebay though it did not list price? I'm curious how much they want/.............