I ended up trying out both versions. The winner by a long shot was the B1 Hardware, using the original 2.00NA F/W.
My test is a 30GB .m2ts (blu-ray) file (2 hr movie). It's streamed from a D-Link DNS-323 NAS to a Netgear EVA9150 Digital Entertainer Elite.
My previous router was the D-Link DIR-655, which worked flawlessly for everything but streaming HD video files. While streaming HD, the video would pause about every 2 minutes or so while the Netgear EVA9150 would buffer enough data so it could resume playback.
All the routers were configured with the same settings. The DIR-825's were set to stream video in the 5 GHz band.
Rev A1 hardware performed slightly worse than the DIR-655, it paused/buffered at least once a minute, sometimes more frequently. It's Signal (quality) was around 45%, but the Rate was only about 55M (on Wireless screen of the Status tab). It was returned.
The B1 hardware with 2.00NA and 2.02NA F/W streamed video flawlessly. I'm able to watch the entire 2hr movie without a single glitch. I must say, that I'm impressed. While it's Signal (quality) was only around 30%, the Rate was about 140M. I'm keeping this one...