Keeping in mind I am discussing E4200 issues, not the E3000 it replaces...
Realizing that 2.4GHz has better penetration than 5GHz I relocated the router to a less desirable location (as in it can now be seen in a living area) in our house to confirm suspicions of structural interference - yes, that is/was part of it. Additionally I have toggled SSID from one single, to unique (as it should be by default in my opinion) just to see what would happen, as one would suspect, my wireless card gloms onto the stronger 2.4 signal and holds a reasonably solid 144 Mbps. When using unique SSID's and locating my laptop within the same room / line of sight, I can usually get 300 Mbps, not the theoretical 450 is it? Yes, maybe I'm asking too much but it sure would be nice to know what one can truly expect from this new hardware, and, it would be nice if Cisco would provide a "rule of thumb" for determining what to realistically expect with X number of walls as interference, etc.
I'm still not totally sold on the deal but as one who remembers being all excited about my first 1200 bit/s modem, one must be patient as technology marches on. That said, I want it to be perfect now! 
Fine tuning suggestions are gratefully accepted....
Dave
