I went with the 65 profile on my plus 4 last year from the 60 as fitted by MMC. Primarily to add to ride comfort but also to take advantage of the slight increase in ride height and therefore ground clearance of an extra 10mm. I checked the speedometer against a sat nav device, road angel, and its reading was spot on! Hadn't checked prior to the change though, although I suspect it probably over read like most cars do.
For me the change has been greatly welcomed as the ride quality is improved no end and I wouldn't say the handling has altered detrimentally, certainly not for the road anyway. If it were a track car I would stay with the 60's as they are more urgent but I really am enjoying the car much more for general driving. Only disadvantage is changing all 5, however they are standard VW Polo tyre's so readily available and cheap for top branded options.