I used to use amplifiers in the early days. But they do seem to be problematic. Also, links can attain greater throughput without them. With the advent of high-powered cards, they are less needed. But if you really think an amp is necessary, I've had the most luck with rflinx bidirectional amps. I've noticed them performing pretty good with prism cards. Most atheros cards I've tested seem to be crap when amped; i'm guessing it has to do with their better receive sensitivity. Most of my client base is in rural areas, so I've not been involved in amp wars, but I can see it would not be a good thing. IMHO, if you need the best coverage get a XR5 card.