I never checked the speed for the reasons you described, and only started to investigate when:
- I noticed that I could not stream Sky Go and iPlayer to the tablet fast enough when too far away from the router (kept on buffering); and
- had some problems when video Skype-ing.
I'll be more than happy if I could get my BB speed on wifi anywhere around the house - around 14Mbps, but I am currently getting only 2Mbps...