Lots of things I can't talk about ;-) but I can confirm that SQL Server is big in many parts of healthcare outside the payers.

Yes, it's getting bigger. I actually talked about that back in 2009 when I was showing people case studies of companies that were chosing MS SQL over Oracle in the vendor selection process.

But "some" of these same places have not been able to successfully transition from Oracle to MS SQL - and haven't gotten to their desired sunset stage. Not because of the technology but because of the proverbial chickens coming home to roost - years and years of patched and undocumented code that places are finding nearly impossible to read through and clean up.

(And that could have happened just as easily the other way)