Check on which version of the Gecko you are about to buy.
I almost bought one at the Southampton Boat Show (a Version 9), which still has the velcro inserts to adjust for size etc. However, they showed me the Version 10, which has a pneumatic insert, sort of like ued on the forces Respirators,where you put the helmet on, open the valve to adjust to size / comfort, and it is an excellent fit. This version is liely to be £10 or so more expenive, but, in my opinion, far superior.
As for the fogging visor, buy some 'Anti-Dim' from any army surplus store (about £1 per tube - lasts forever) - apply to visor - no more fogging