Having finally despaired of Accuroute, I was advised on another thread of the above two devices. The fellow who told me about them (runningdan) hadnt used either and I wondered if anyone had.
Should I read anything into the fact that the Silva device is called "online"? It doesnt need linking up with a PC or anything does it? It looks the better of the two. For what its worth, its mainly (though not exclusively) off-road routes I need to measure.