Bought
this one last year when I bought the boat. I'd say it was absolutely indispensable, especially since the boat had leaks then (no longer does). Being a desiccant type, it produces some heat and does not freeze over at low temperature, so in mild south coast climate you probably won't need the tube heaters at all.
It's been a year and a half now and it has been in use for most of that time, including occasional use for clothes drying inside the cabin on rainy days (simply hang up clothes in a cabin with the dehum, set to clothes drying mode and close the door). Also handy when drying out plywood that had gotten wet from a leak, and I've even used it to dry out difficult to access bilge areas. It has a condensation tank and also came with a piece of hose that can be plugged into an opening on the back and plumbed into the sink when leaving the boat for a while.
Didn't catch fire yet and I doubt it's any more likely to than a shorepower charger or fault in the DC system is, although it developed the occasional squeak - probably wants a drop of oil on the fan bearings. I've also made the mistake of using it while varnishing some things inside and it has taken on a bit of a smell from that (luckily not synthetic varnish, so harmless).
Would recommend getting one. If you have a hygrometer (most cheaper digital weather stations do), you can easily tell if you're at risk of mould growing: only happens above 65% relative humidity (also only when spores are present - more of which will be flying around in marina air than on swing moorings).