Both systems are very good, but only LXNAV allows you to customize *everything* as you wish. Whether its on their desktop tool for upload or directly on the hardware itself, its pretty easy and quick to do.
Sure, Clearnav allows you to turn on/off info boxes, but if you want to see those boxes in a different spot, your stuck with the placement they've already chosen for you.
Maybe most users dont care, but for the amount of money in these systems the ability to customize what you see should be standard. Its just a bunch of 1's and 0's, let me put 'em where I want 'em

(my opinion of course)
Support from LXNAV and their dealers is top notch too!
Britton
(prior Clearnav user, current LX9000 owner)