Depends what you mean by a thru hull
If you mean one that sucks water
into the boat, and uses this to cool the system - better than air cooled, but uses a lot of power to suck the cool water
in and pump it around.
If you mean the one that has pipework outside the boat which contains the condensate - I have always woried about the vulnerability of this system
If you mean a thru-hull fitting that is a large blob of bronze, and this acts as a heat sink, thru which the condensate is pumped - I have no personal experiennce, but reports from a number of people I do know, who have used this, are that it is by far the best system, and the most economic in use of power. It looks like this:
I would definitely fit this myself.