I too sport 13.4s and am generally very satisfied. However, the 'clamp pressure' is fixed - my bonce is a tad larger than average (but only on the outside) and they can squeeze a little after a few hours' wear.
Taxes: Some states (e.g. Louisiana) refund sales tax (9%) if you depart with an international flight ticket. I believe an alternative loophole is to order online from a different state to the one you're visiting, for delivery to your hotel. But of course (ahem) you'd be liable for British excise duty if they're worth more than 145 quid. Even if you're wearing them...
