If faced with those 2 choices I go Russell.
I have been using a 550 Nuvi on my GS now for about a year. It works GREAT. I use the battery power only and do not have it hard wired. Battery life is listed as 8 hours and I get well over 6 hours. In addition I have an extra battery (buy them on Amazon for about $20) and can get more than a full day. It is VERY waterproof! [url]http://www.youtube.com/watch?v=ALDiGADCl9c[/url] . It does a great job and you can get RAM mounts to mount it most any place you like. For about $200 I think it is a great alternative to a ZUMO. I do have a ZUMO 450 on my RT and it is a wonderful unit … but costs about twice as much. As others have noted … Nuvi is not as easy with gloves … but then I try and NOT use it while riding and simply pull over when I need to enter info. Just my $.02.