Yes I get the same booming sensation with the roof up at speeds over 60 mph.

Its like a fluctuating pressure boom which some people are more sensitive to than others. I believe it is caused by the roof flapping - you can see the rear window moving/buffeting at the same time. Mentioned it to the dealer as my MR2 roadster did not suffer from this and had a soft top and was told its normal (as usual).

I am more sensitive to it than my partner and find it a little annoying when trying to cruise at 85mph.

Initially I thought it was being caused by a slight wheel imbalance but I am pretty sure its the roof buffeting. I did read a road test on the car and the reviewer also picked up on this.

The other strange thing mine does is make an intermittent rushing wind sound from the roof in synch with the windscreen wipers as they reach the top of their stroke - a bit poor really - no such design faults with the MR2 roadster.