I've been asked a few times about import units, and what's my view on these, well the simple answer is there OK, if you walk into a shop in the UK you can spend £800 on a unit and you know if you have problems you can normally take it back depending on the time frame and youll either get help off the shop or at least the unit is sent away for repairs/replacement.
The import units may be less powerful in some aspects but they still do the job they were built to do, a large selection is out there from resolution size, wheel control, Freeview TV, removable screen, Bluetooth, GPS, TMC, the list goes on and on.
The reason why people ask is simple: To save money.
A lot of threads say dont bother, Id say make up your own mind, just cos its on a thread doesnt mean its good advice, pick a few units, look in to customer reviews and make your own mind up!