Whats the point of all this? To pick up more WiFi hotspots?
I get the fact that you can add a tin can and get better reception, but why don't you just go and make your own? I designed a 2.4GHz Helical Antenna that has approximately 15 dBi of Gain compared to your puny 5-7 dBi(even with the 3 dB from the backplate). I made it out of PVC pipe, wire, a 1'x1' aluminum sheet, and some wire. You'd have to test it to make sure it hit the operating frequency, but it only cost about $50 and you could easily pick up wifi over a mile away.
Good luck with that, the most manufacturers use the max power rating of 30 dBm or 1W, which is the FCC standard for ISM band. As for the receiver, sensitivity will only matter when your signal is bottoming out the noise floor. With a better antenna you effectively bring the signal level up, thus offsetting the sensitivity factor.
Source: I'm an RF Engineer.