Thanks for replies guys. Dealer said up to 45-50mph heritage should ride quite smooth due to counterbalance, after 50mph road king with its rubber mounted engine is the way to go. I don't mind the vibration though, before buying this bike everyone always told me Harley's vibrate like crazy, so I was prepared for it and assumed it was normal. At least it's not high frequency buzzing like on Jap bikes which makes hands go numb.
At 80mph forget reading a license plate, I can't even make out if its a car, a truck or whatever behind me! Btw, clutch was adjusted 3 weeks ago when bike was serviced. I don't have extended warranty or service plan, dealer didn't offer it.
I just love this bike though, why didn't I buy a harley sooner! I shall adjust my technique and see what the difference is.