No, the EXS will not give you less range. They both operate at 100mW, and have the same basic range. The driver issue is moot, as there is a new driver now that works just fine with it (search for Atheros, it's one of the newer threads...) Yes, its a Gigabyte card with an Atheros chipset. Atheros is simply a chip maker, they depend on the big manufacturers to utilize the chipset in their own designs. If you don't need 802.11a, then don't bother. I have never used A in all my time using wi-fi. Either way you go, its a damn good setup. I have found access points that I have never been able to see with my 3945.
Here is a link where you can pick one up for 26 bux, however I cannot vouch for the seller. If I would have found this before I bought mine on Ebay, I would have given these guys a shot for sure. Good luck!http://www.ewiz.com/detail.php?name=GN-WI01GT