OK...

The StreetPilot III is awesome, mainly, IMO, because of the color screen. It just makes it sorta easier to make stuff out. As far as navigation goes, i believe they are exactly similiar. The V gives you the arrows and a visual representation of what you're supposed to be doing. Where the V gives you beeps to notify of turns, the StreetPilot has got the advantage of voice prompting, however, i'm not sure how well this would work. Sometimes these things give you directions too late, and then start giving a slew of directions as they catch up with themselves.

What i like about the V though, is its size. This makes the screen smaller, but i think its worth it, and anyways, you get used to it. I'd say if you were planning on mounting it on your bike, the V would be easier. I'm sure you could get the StreetPilot mounted, but it might be a distraction.

The streetpilot also gives the advantage of the 32mb memory card, on to which you can add as much as 96 more MB. The V only comes with 19mb. On my V, i have all of LA, San Bernadino, Orange, and San Diego Counties loaded. LA county took the most space at 7 mb, so take it from there. If your'e planning on doing a lot of traveling, you might need the extra memory. But if not, i think the 19 is plenty. Plus, its not like you're screwed if you don't have the residential level detail, but it IS nice to know where all of the Dairy Queens are around you.

As far as battery life goes, i'd say i've put about 12 hours of life on the alkalines that i put in there when i got the V, and its still going, but it won't let me turn on the backlight (which kicks ass by the way, however, i think the color screen out does it). I'm planning on getting some rechargeables from thomasdistributing.com. I know the V has the option to choose weather you're using NiCads or Lithium Ions. I'd go to the boards on geocaching.com , they have a cool hardware forum where thats a talked about subject.

Anyhow, i hope this helped. For me, doing all the research about them was half the fun of buying one. I'm totally stoked with my V, and i think Loren will agree with me that V is a kicksass toy. Its got its drawbacks, but its still being improved. They just recently put out a nice firmware update. Also, i think with the V you can get a nice little deal where you get the unlock codes for the whole US for an extra 50 bucks. Pretty nice.

PM me if you have questions.