GIANT THANKS to the OP. Stumbled on this post and went hunting for info and found the post @ XDA. I bought mine in early February with the replacement plan (ADH). Packed mine up last night in original packaging, w/ original receipt, and hit the BestBuy near my office about an hour ago.
Took it to Customer Service and nicely explained the poor WiFi/GPS issues. Explained that I'd heard they might be able to replace it as a Manufacturer's defect and that it had been replaced by ASUS with a newer model that fixed the issues. The lady's first statement was that they would probably only be able to ship it off for service, but after punching a bunch of stuff in her computer, she determined that they "no longer send this model off" and that she could give me a store credit to replace it if I wanted. She looked up the Infinity, confirmed it was same price but none in stock, and ordered me one on the spot! Even gave me a pro-rated refund on the ADH...Jackpot! Infinity should be here 8/13!
All said, probably took 10 minutes total. I've always had good luck with BestBuy and enjoyed shopping there...and certainly glad I held on to buy the Prime (r.i.p) from them earlier this year!
Also...here is a giant post @ XDA with LOTS of stories, suggestions, news, etc. on this:
Best Buy Exchanged my Prime for an Infinity - xda-developers