Are NHT VT2.4's harsh, or is it just me?

If you want to "push" the woofer break-in, aim the speakers toward each other, wire one out of phase, turn the bass up, and let 'em pound away for a few hundred hours.
THEN listen. The tweeter will still be bright because that's what NHT's always been about, but at least you'll then be able to give them a fair hearing....
I wouldn't be surprised if you still found them a bit wanting...due to a "U"-shaped spectral response...the old west coast sound. You can modify the bass end with room placement, but the midrange will probably still be pretty sucked-out vis-s-vis the treble. Do these come with a tweeter pot or switch?

Your ears are indeed accomodating throughout a listening session, ESPECIALLY if you listen at high SPLs. I was at Boston's Symphony Hall last Wenesday for an open rehearsal of the BSO with guest Andre Previn conducting the Ravel Left-Hand Piano Concerto with Thibodeau (sp); I was in 6th row center, and the opening orchestral minutes were breathtakingly beautiful and LOUD. Then the 9' Steinway entered with a thin, wimpy sound! Sounded like a fortepiano!
I then remembered that I was sitting slightly BELOW the
soundboard, and well below the lid's projection, and that the front orchestra seats are simply not kind to pianos at SH. Yet within about 10 minutes everything was fine. Did the piano change? Of course not. Did Thibodeau get MORE dynamic? Nope. Just pychoacoustic accomodation.........
Your NHTs WILL continue to fill out their bottoms with time, but I suggest you either be patient, and NOT force it by ruining your ears in the meantime, and perhaps follow a prescribed artificial break-in as described above.
I'll bet that when you listen tonight you'll be disappointed with the first two minutes of music because the sound IS still thin and too analytic. You need to give the woofers' spiders and surrounds time...not blast your ears into submission! Take it easy....