I use the Garmin Vista HCX on a RAM mount on my MTB. The RAM mount is a heavy duty cradle that mounts solidly to the handlebar; I don't worry about loosing it. I also have a Cateye cyclecomputer along with a Polar HRM watch. The combo works well together. My MTB looks like a electronics geeks heaven as I mount the watch, Cateye and Vista together on it if I a not familiar with the trails. I can use the Vista on hikes or on the Road bike with the street maps (which I added to it), or off road with the TOPO maps (more detail than the basemaps). I use the Polar HRM when exercising or hiking, and can leave the Garmin at home on familiar trails and use the Cateye. I thought about the 705, but it's not the best for offroad trails or when I use the HRM for exercising.
Tzvia- rollin' slow...
Specialized Ruby Expert/mens Bontrager Inform RXL
Specialized SWorks Safire/mens Bontrager Inform RL
Giant Anthem-W XT-XTR/mens Bontrager Inform RXL
Fuji Newest 3 commuter/mens Bontrager Inform RL
Novara E.T.A commuter/mens Bontrager Inform RL