I'd watch this video first and take note of the bench mark specs...
... and then compare the geek bench results from the i7 CPU upgrade on the base model.
http://imgur.com/a/Lql7v
The base model offers better speakers, battery life, and CPU performance based on the i7 upgrade and the GPU difference wouldn't really be noticeable, even with the slower RAM clock over the standard TB version. So I think the upgraded i7 base model may actually be a better buy based on this for the very same money if you weren't interested in the TB itself?