I have one of each, and they are both great bikes in their own right. The 700 does breath easier on the highway well up into the mid and high 70mphs, but the 310 does well in the high 60s to low 70s also. There are more luggage options for the 700 as they have been around longer. The 310 is a deffinate hoot of an around town bike and gets better gas mileage if that is a concern, but does have a smaller tank so the range is shorter till the low fuel light comes on.
Hope this helps instead of confusing things.
I've put 10k on the 700 this past year and 3k on 310 since october.
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