I have just got a Navman Pin 570. It comes with SmartST which does a great job in the car. I loaded in Memory Map which means I have a scrolling OS map in my hand for when I get out of the car. It also came with a database of not only all the speed, sorry safety camera but also the locations of laybys, etc where they setup mobile speed cameras. It is a PDA and plays MP3 files. Not cheap at £230 plus the cost of Memory Map but some satnav systems alone cost much more. I am chuffed to bits with it. The only drawback is battery life at about 3 1/2 hours which is OK for most geocaching but not for a longer day out on the hills.
I still have a Garmin eTrex which will stand rough treatment better and the battery lasts longer - no satnav though.