Erm, by saying same wifi-n spec, what are you implying?
There are a lot of things that affect wireless throughput even when the comparison is being used on two or more devices are based on the same chipset. Thats because the throughput does not only rely on the chipset, but also taking the consideration of the number of antenna being deployed, type of antenna, interference level, etc.
I too dont buy this bullshit before I tried it out myself.
I had this DIR-655 and was using Belkin N+ adapter from my pc. Transfer rate at best was 6MB/s. I add another router which is Apple Time Capsule to the test and gets around the same mark. Then coincidently, my uncle ask me to help him purchase a wireless adapter and I settled for Dlink DWA140. I thought it should be worse than the Belkin due the price I paid for it, but to my horror, it was WAY WAY faster. The speed always in the 10MB/s zone or more. I thought must be same brand thats why its faster. Connect it to my Time Capsule and same result.
I googled up and find out that both are using RT2870 chipset. Then I prick open both and saw both also sport two antenna. And I even used the same drivers from Ralinktech to level the playing field. Result are the same... Dlink consistently outperform the Belkin.
The same applied to mobile phone.
so u see... 6 vs 10 it's ~200%... but read the benchmark and see what the reviewer "accepted" for the result...