Threshold s1000

I bought these 2 monoblocks a few years ago and spent quite a bit of money updating them to better components and putting in balanced input sockets. This was quite easy I am told, due to the very open architecture and fundamentally solid design. I like them very much and I was recently demonstrating them to a potential buyer, versus  his classe 350 monoblocks, and the thresholds were in another (better) league entirely.
I cannot find any internet information about them and I am inclined to keep them in spite of 2 separate offers from Italy of €4,500. I am reluctant to send to Italy because of potential damage and or disappearance of the 2 heavy boxes to such a  notorious country for causing problems. In my system they are up against Bryston 7b3s (or Bryston 4Bsst2 in my second system) so they need to punch a bit of weight. Just wondering if anyone knows of these rare items and what I might expect moneywise if I ventured to sell as I have too many amps. Something has to give. I know people will say listen and make up your mind, but they are quite different to the Brystons so it all depends on mood and synergy. I could argue for both in their own way, so  I am wavering all over the place