Feisty, I had a look at those....nice looking units....but, the need to access the usb socket would have been a pain for me.....as access to the rear of where the unit was going would have made it impractical .
The unit I installed has highlighted a problem with most vans...the aerial. Reception is nowhere as good as the 4wd, only because the aerial doesn't mount to a big lump of steel, only composite type panel.
Solution....at this stage, a length of wire attached to the aerial for areas that have weak reception. A longer aerial MAY do the same, but haven't tested this yet ?