Climate and in particular rapid changes thereof have more serious effects on high tension harps with solid wood sound boards than on those like the Ravennas, Rharp Merlin, etc. with medium tension and laminate boards. Laminate has an undeserved reputation as “lesser quality” for several reasons: it does not improve in tone as much, and until recently makers did not take as much trouble to tune them as they do with spruce, cedar, redwood, etc. This is a constant discussion among makers but one thing no one denies is that it is much less susceptible to humidity issues.
A good rule of thumb would be “if you are comfortable, so is your harp.”
Biagio