I've been an owner of a 2003 Express 330 for the last 15 years and owned a Marlin 30 for over 5 years before the 330. I've experienced many GW hulls, and the Marlin and 330, in my opinion, are among the most seaworthy and versatile. The Marlin walkaround feature was a dream for fishing, but the trade-off was pinched-in cabin space. The Marlin helm area also was not that spacious, and some angler guests had to sit outside in the aft-deck. All of those seating/comfort issues were solved with the 330. Also, my small family (4 adults/two grandkids) can enjoy So-Cal weekends at local islands. Of course, the 330 does not have the fishing walk around security of the Marlin.
I did not have any problem with moisture issues on either boat, but I was very anal about inspecting/changing the transom cap (bang plate) and bronze thru-hull drain tubes - arguably the biggest problems leading to transom rot. Some 330 owners have suggested that the rear quarter vent plates may be a source of water-intrusion, but mine seem OK (very lucky to live in relatively calm So-Cal waters).
Of course, any boat with Yamaha 225 4-strokes is likely to be plagued by early corrosion failure. I re-powered my 330 (225's lasted 1,400 hours) a few years ago with Yamaha 250's.
Good luck on your search!