It did look like the numbers weren't quite as good with the 2.4 GHz band, but I guess for me, that's the unimportant part of the story. Everything I wanted to do over the network (email, streaming media - Netflix, Youtube, HBO Go, etc) worked fine with no noticeable slowdowns, buffering or anything (and streaming was still in HD). So, while the numbers aren't quite as good, the ultimate effect was - it seem to didn't matter with real world usage. Anecdotal, I'm sure, but as long as it does what I want it to without any adverse effect, the numbers really become meaningless.
For others who have different WiFi usage scenarios, maybe returning until its fixed is best. For me, the WiFi does what I need it to without any noticeable problems, so I'm keeping mine. If Google does bring out a refresh or new batch of units with better WiFi before the warranty is up, sure, I might RMA it but I don't see any pressing need to right now.