I have used the original Tomato ND, then the Tomato ND Speedmod on my Buffalo G125 for a long time. There were some features that never worked for me, probably Measure Noise Floor and Bandwidth Monitor. My wireless connection fluctuates, and I have to manually change channel by trial and error to get a more stable wireless connection. In the best case, I got a low quality signal at 48/54Mbps connection. In the worst case, the connection slows down and eventually requires a reboot of the router and a quick channel change before it deteriorates again.
I have just discovered that TomatoUSB seems to have a newer Broadcom driver, so I upgraded to the Kernel 2.4 NoUSB Standard Build 53. I'm happy to report that all features that I've tried are working, unlike the original Tomato ND. As for the wireless connection, the behavior is very different. Upon initially connecting at 54Mbps, it'll fallback to 24/36Mbps at high quality (viewed from PC client) within 30 seconds no matter which channel, TX power, or a few other wireless parameters I tried. I guess a high quality 24Mbps may be more stable than a low quality 54Mbps, so I hope it'll be better for me.
With this new firmware installed I can also scan for nearby WiFi router/AP with more results. At one time I think I saw 14 (I live in Hong Kong), occupying not just channel 1, 6, 11 but intermediate channels as well. So is there no hope for me to get a high quality 54Mbps connection ever? Perhaps my next router must be a 5GHz model?