I had a Zenec NC2010 and the CAN gateway is not an issue as it is with later OEM HU's. it's now in the wife's car.
If you search for 'NC2010' you'll find pics I once put up.
The Zenec has much more standard spec compared to an RNS510 and is designed for the mk5 chassis, so has perfect integration and MFSW/highline compatibility. Parrot bluetooth with use of telephone button etc and when upgraded, a far superior Satnav.
I paid £450 two years back, how much are they going for now? The NC2011D is the later model.