Personally, I would prefer a dividend to a share buyback,...

Personally, I would prefer a dividend to a share buyback, especially if the company is under-valued. Declaration of a div. would do more for the share price than a buyback I believe. A number of companies making buybacks have not made any appreciable impact on their share price - witness TLS, SDG, RIO and I am sure you can quote others. I think tax issues may come into buyback vs div.
However, I do not expect either buyback or div for SLR (not at present anyway). $83M in the hand may sound a lot but it soon goes if mine development and processing plant extensions are engaged in while aquisitions could also consume it.
In the absence of an update in AISC, we need to maintain the previously stated figure ($1350/oz for mid-range of guidance) and so still a bit expensive in that regard but nevertheless on an EV to annual production basis it is looking good.