I've got full length mudguards Gaz, and they're the SKS Longboard variety too so yes, wheel spray is significantly reduced. However, as pointed out above, they do nothing to stop you getting wet from failing rain, or as was the case the other day, horizontal super-rain.... Oh, and those mudguards also did nothing to prevent the pure comedy moment that was an artic going through a huge puddle and drowning me in a wave of spray as I cycled along the designated cycle path (pavement, running against the flow of traffic). I laughed, really I did.