SSpiro? WPA Encryption Wifi?
There was an issue with some chipsets and early Pre-N wifi routers, whereby the symptoms you are experiencing above would result from the router not accurately supporting WPA encryption. I had this issue and had to replace my Belkin Mimo Pre-N router as it was the issue not the Mac or the wireless drivers.
i believe most Pre-N routers all used the same chipset Linksys WRT's used with the same underlying problem.
There was no fix because the router manufacturer's were **** and said "we don't care, buy another router"
You can try running with WEP/no encryption (same thing really) for a short time to see if you're issues are alleviated. If so, you know what you need to do.
Sorry, but the truth is that this is solely Apple's problem. If you install Windows or Linux on your Apple hardware, you will see that the Apple Airport card will "just work" with all those routers that you are mentioning. But as soon as you use Mac OS X Snow Leopard, the very same Airport card in the very same computer will become an unreliable piece of trash. Switch back to Linux or Windows, and the card will work again. Very easy to reproduce.
So no, this is NOT a problem of the router manufacturers. Apple screwed this up big time.
You know what's even more annoying? When you buy a cheap USB stick with a Ralink chipset and install their third party drivers, wireless will also work in Mac OS X, fast and reliable.
So you basically just need third party hard- and software to get a working WLAN with Mac OS X. Just don't use Apple's buggy software which they obviously do not want to fix.
The only people who do not seem to have problems with Airport cards are those who are also using Airport base stations. If those two were Microsoft products, everybody would be speculating that Microsoft, evil as they are, had implemented it like this on purpose to sabotage third party vendors. But since this is Apple, of course, naturally, it's everybody else's fault, but not Apple's.
To answer the OP's question: I haven't tried it and honestly, I no longer care. The USB stick solution works perfectly for me and I no longer waste my time on trying to fix Apple's problems.