I store mine in its plastic box along with probably 8 in every 10 shooters I see.
The other 2 in 10 keep them in alloy cases
Condensation does not appear to be a concern - maybe if you kept it in a unheated garage or shed it might - but not in a centrally heated house.
Most of the time I do unscrew the cylinder a turn or so which depressurises the action and insert the thin plastic spacer that Morini provides for just this purpose.
I don't think longer-term any seal benefits from being kept in a compressed state and its safer of course...but I'm equally sure there are many that keep theirs pressurised with no ill-effects.
The screw threads only locate the cylinder, they do not provide the seal and they are hard anodised anyway - I doubt unscrewing them one or two turns once or twice a week will wear them out in a lifetime of shooting.