Along with the constant humidity, I also have consistent cool temps - never above 65' under the hottest August sun. I have considered going sealed, but then I would have heat to contend with and the added cost of C02.
To me, it is more economical and in my favour to deal with 65' ambient with the higher humidity. Maybe I have been lucky over the years but I have only had one brush with PM - a small blue moonshine that was tucked in a corner my very first run. Switched to 24 exhaust and better circulation and have not had a relapse since.
I just increased my space a little recently to 7x6x6 to accomodate a stretchy wild Brazilian. Stripped lights of hoods and hung vertical. 400MH, 430 Agro and 600 Sont T with 420 CFM changing air just over once a minute - plants are loving it!
In retrospect, all my best sativa's have thrived under these conditions, but then again the tropics can get very humid can't they?
Oh - and GREAT to see you back friend ;)