Quote Originally Posted by OakLeaf View Post
If it's important to you to "target events when I experience symptoms", then grade of hill is something to consider. It's the nature of GPS to be quite inaccurate when it comes to elevation, and none of the Garmin wrist-mounted units offer barometric altimeters; still, the GPS data would let you note which hills were a problem for you, and compare them against other hills in your area, etc.

I believe that the 310xt cannot give HR alerts unless you program a workout (which can be a very simple workout that says nothing but "maintain HR between X bpm and Y bpm). I'm not sure about this, since I use HR during the workout only when it's a multi-step workout I've programmed, but I seem to recall complaints about this on the Garmin forums.

Just FYI, the 705 can navigate you in your car as well as on the bici. It's not ideal - the screen is much smaller than motor vehicle units, and works in portrait mode rather than the landscape mode that most motor vehicle GPS use - but that's something to consider in terms of value for your money, since you mentioned the value of having GPS without navigation.
Thanks for the input, OakLeaf... The hills as a reference is something I've given more though to, especially since that's where I'm most likely to peak.

Hubby has a 705, which is really cool. Just not so great for the usual gym stuff. --shrug--
We plan to use the nav features when we take our bikes on out of town trips so we don't get too lost. Would be nice to be able to get back home if I get lost out in the country on a solo ride.