Hi Brian,

I've the 500 for a year now and I'm very pleased about it.
Batterie life is about 5hrs when one 1 sec. update.
The only drawback is the minute font size.
But maybe mounted on a yoke that is not much of a problem, mine is
attached to the panel since I've a stick.
Also very nice is that the complete package is ready to go.
My earlier GPS shortcircuited while I was on a vacation abroad, not
very handy I can tell you.
So I bought a 500 on the spot, put in the batteries, read the manual,
duct-taped the lot to the panel and I was on my way again.

-Kees