3.1 model is really just 10 to 15 seconds faster than the base model...
10-15 seconds faster at doing what?? The time difference depends on the task...
Consider that the 2011 model will include Lion while the 2010 will be Snow Leopard - that adds $30 value to the 2011, plus thunderbolt port and the ability to add up to 32gb of RAM instead of maxing out at 16gb (not important today but later on....)
I would incline to the 2011 model just because it is newer, Sandy Bridge chips..., and will have a slightly higher resale value because it is a new model.
Also, you can use this link to check or get emails when the model you want is back in stock
http://www.refurb.me/us/