If I had it to do over again, I'd say "screw it" to the Zumo.
I bought the ball and chain a refurbished Tom Tom One from tigerdirect.com for $149.99 a couple months ago. Has about a two hour battery back-up(like the zumo), BETTER and more accurate maps, bluetooth links, traffic and weather that connects with your phone (instead of having to pay for xm-radio extra service for another $7 a month, and the zumo's versions suck, tomtom's are really decent, and show great satellite weather that riders would want, i.e. when the storm front they just rode into will be over with), FREE map upgrades instead of only 12 months.
No, it's not as water-resistant, so get a ziplock baggie in case you get caught in the rain.
No, it doesn't come with a bike mount (does come with a car mount), so you'll have to get a ram-mount for about $40, and plug it in to your aux plug or get a second power cord and hot-wire it.
But sheesh, man, it's almost $500 cheaper and does the same stuff...much of which it does better, in a smaller overall package with the same screen size.
here, it's at circuit city for $149: http://www.circuitcity.com/ccd/productDetail.do?oid=191752&WT.mc_n=67&WT.mc_t=U&c m_ven=COMPARISON%20SHOPPING&cm_cat=PRICEGRABBER&cm _pla=DATAFEED->PRODUCTS&cm_ite=1%20PRODUCT&cm_keycode=67
or if you have an issue with refurbished, pay another $40: http://reviews.cnet.com/car-gps-navi....html?tag=also
buy it and send me $550