Sky do employ traffic management - they call it DLM - so just be wary before moving (and yes it is buried within the vague FUP and not advertised in flashing lights on the Sky webpage)
Check out Sky forums on Skyuser.co.uk or thinkbroadband.com to get a view on what you can expect. As mentioned unless you live next door to the exchange you are unlikely to get full 16Mb - Sam knows!!
btw, I am ex Sky broadband - but no grudges to bear. I was 4 miles from exchange so was limited to what bandwidth I could get thru ADSL