Have you driven the car with and without the dynamic handling package? BMW has made what is in their "packages" incredibly confusing (at least if trying to compare year to year or model to model). I have never driven a GT. However, I have an 04 530i with the "sport package". Now, most of the "sports" packages are nothing more than cosmetic changes (and an "increased top speed limiter" -- which I've really been wanting because I get so tired of having to cruise at only 150!). Back then the sport package actually meant something and included the active steering and something then called "active roll stabilization". Once I drove one with this, I was hooked (and I live in ND where I have to search out corners). The words "go kart handling" used above are a good description. Another way to put it is that I also own a Porsche 944 Turbo, and my sister has a Cayman, and the 530 corners as good or better than the Porsches! If there is anything loose in the cabin, it will be flying across the car if you're not careful because with no body roll you corner like a beast -- but the centrifical force is still there even if the lean isn't.
In fact, if the GTs you were looking at where the xDrive variety, I'd probably be trying to convince you to buy the other one and find out where the one with the handling package. Finding one with a sports package isn't too hard, but I have yet to find a used xDrive GT with the handling upgrade. (I'd like to consolidate my 530 and X3 into one vehicle!) Kinda sad actually that even BMW and it's drivers have come to define "sports" in terms of how it looks rather than what it actually does to performance. Ultimate "looks like it's hot" Machine??? (Excuse my off topic rant!!)