I probably have only put another 20 hours on them (I'm not long back from vacation) so now around the 60 hour mark and I have to say they are definitely improving. I had my son over and asked him for his thoughts and he couldn't hear any distortion that he didn't think was deliberate - i.e. closed miked guitars on some Beatles songs.
My partner who originally described them as 'toppy' now thinks they have mellowed.
I had my Linn LP12 upgraded and spent a bit of time over the weekend listening to vinyl and had a thoroughly enjoyable time. The mid-upper frequency harshness is definitely greatly reduced
I'm a happy (well happier) man!
Stay with it. It took several hundred hours for mine to really get "broken in." I'm more than satisfied at this juncture. I did put on CDs of organ music and set "repeat" before leaving the house. I'm doing the same for the SS2.2 Smart Sub.
One other suggestion: The 2.7s, like all of the floor-standing Thiels, are power hungry and have lower than nominal impedances at some frequencies.. Be sure your amplifier can put out clean watts when the impedance goes down to around 2 Ohms. (I'm driving mine with a Bryston 4BssT2)
Just give 'em time. They'll give you years of pleasure.