The threads on the Tavor barrel are 1/2-28 threads, like the AR-15 type barrrels. So yes the muzzle break can be changed.
At first, only CanadaAmmo had access to Tavors.
Now pretty much any firearms dealer in Canada can sell them, through North Sylva (distributor).
The Tavor is now available in the U.S. IWI U.S.
Keep looking, they are not easy to get but they are out there! A fellow American Tavor enthusiast informed me (Dec. 2013) that IWI U.S. offers a service to convert your Tavor for left hand use. You only pay the bolt, and they ensure proper head space. Check with them! I have never heard of a similar program in Canada however.
I did not for the simple fact that I do not have the money to buy all and every model. I do not have a supplier from which I can borrow optics (although I would be greatful to anyone willing to lend me optics to try!).
For any comment on this site, email me here: lt at ltwerner.com.