Ive got a shotmiser g300 which is able to be used as a sat nav, think you need to install the sat nav software which is around £60 i think. Golf wise i cant recommend it highly enough.
Been using my Snooper S280 for over 2 years and swear by it. I think it's now discontinued but you can still pick them up reasonably priced.
I was playing at Bulwell Forest which has a main road running next to the 4th (?) fairway and the Snooper warned me not to exceed 30 mph - it has a speed camera detector as well as a car Sat Nav so watch out if you play a course bordering a main road. Lifetime free updates for Sat Nav, Speed Cameras and Golf GPS.