If you're looking for a GPS that is portable, for use on a mc, in a car, truck or while hiking, take a look at the Garmin Quest II. I've been researching for some time and this is the best I've found so far for my needs. It also uses flash memory instead of HDD, which makes it a much better bet to withstand the vibration inherent in mounting any GPS to a mc. It comes preloaded with detailed base and street maps for the entire USA. Waterproof, lithium ion battery for up to 20 hours portable use, and can be hooked to your mc or car power supply if you wish. Also very small, voice directions, all the usual additional features, mounting hardware available for mounting to your mc. Small enough to put in your shirt pocket.
There is no GPS currently on the market for someone looking for a unit that will fully meet your needs for mc, car or truck, marine, geocaching and hiking use, but the Quest comes as close as anything I've yet found. I'm still looking but will probably go with the Quest II shortly. I've found it as low as $540 delivered via an Internet vendor.
Lee in the Mountains of Northern California