The issue about not using it while you’re there is that they don’t want people trying to claim a VAT refund for something they already owned, which you obviously won’t be doing. You will have all the appropriate documentation (receipts, VAT form). I think it’s very unlikely you would run into a problem if you use it (gently) while there and it still looks like new when you leave. You could put it back in the dust bag and box for when you go through the VAT process in the airport and then use it again when you’re done. In many, many trips to Italy, I have never been asked to show my purchases, though I always have them close at hand in case they do ask.
It looks like the price difference now is about $500, not counting the VAT refund. On the other side of things, that also doesn’t take into account any duty you might owe bringing it back to the US.