Having a demo unit is marketing hype--just like the WZR-HP-AG300GH. You can make all the claims and fulfill all the marketing bullet points you like, if the product doesn't work it's all pointless. The WZR's box was filled with bold claims: high power, etc, etc. None of those claims rang true in my expereince, or in the testing at smallnetbuilder.com. While the ability to run DD-WRT was appealing to me at first, at this point I believe it's a hinderance and part of the problem. They development of DD-WRT may be as flawed as Buffalo wireless products themselves. DD-WRT looks great and has tons of features on the surface, but I'm not convinced it actually works very well underneath all the flash.
D-Link makes a wide range of consumer and proffessional networking products. I disagree with your claim that they do not identify hardware revisions. Both the units I purchased were identified as such both on the units sticker, as well as on the title page of each page in the UI. I had no issue locating and applying firmware updates. One of the particularly nice things about the D-Links is that they have their default IP and login info printed on the sticker of each product. You can also access the web UI by typing something like http://dlinkap. That's a great and thoughful feature with years of experience behind it. For my Buffalo's, I had to dig up an obscure, add-on piece of paper which came in the box to get the default IP. The D-link's were very quick and easy to setup, and have "just worked" since.
I had TWO of the same Buffalo wireless units, and they were both heavily flawed in the same ways.
o I had to reboot them both on a regular basis
o WAN connection was unstable
o at one point, they both became completely currupted recquiring complete reflash and setup
o the 2.4 wireless radio turned off consistantly and had to be restarted
o the UI was slow and inconsistant
o the cases are cheap and toy like
o software support non-existant--there's been one update in almost a year, and it broke about as much as it fixed.