I've taken out loans to play tax games before. However, when I've done this, it has been on the knowledge that I could pay it off within a few months, as opposed to a few years.
You owe $2100 in taxes, so I'm assuming you already have the cash to pay that? i.e. by saving the $1600 in tax payable, you would need to find (borrow) $8.4k. In other words, you are getting an instant 19% return on the borrowings. What is your actual savings rate like? i.e. if you targeted repayment of this loan, how soon could you pay off the $8.4k? If you can get that down to less than 6 months (an arbitrary number!), I'd say go for it.
That said, this is coming from someone who burnt his fingers buying stocks through the GFC from 0% balance transfers, so take it with a grain of salt!