I've been gigging the G70 on the shore for two years now, often under those humid conditions. Before that, the G1000 for eight years or so. Before that, the G800.

No problems whatsoever (except due to direct sunlight!)...

You don't have to baby them, Roland arrangers are close to bulletproof...

(My usual disclaimer... Your mileage may vary, objects in mirror... yad yada yada. I ALWAYS use an ATA flight case, Always cover it on breaks, ALWAYS power down on breaks, ALWAYS wipe down at the end of the gig, and do a deep clean every month or so. My eight year old G1000 looked virtually showroom when I sold it. Mistreat ANY keyboard, you'll have problems, but normal caution is enough to keep Roland's ticking along just fine).