Yes we do. We don't care about Windows version @ all as we don't exploit anything special present on server-only versions of OSes from Microsoft. Server line is supported for production but it's just to make our life easier not to struggle with too many versions. But it's definitely not your case.
We're hardware and software agnostic so don't care much about RAID level you use (well, nearly... There are issues but not in your case again).
Strange question

It's like "Should I buy your car from you or just walk away?" (c) ... Of course it's better to use StarWind for everything including ordering Chinese and baking donuts! Kidding... For your task the answer is going to be "it depends". Try both (S/W Vs. CIFS), do some tests and answer your own question yourself. It could easily happen on your particular load scenario and data pattern StarWind built-in deduplication and advanced caching are not going to be any good in saving you disk space and shrinking backup window.
ghost wrote:This is serious question
Is starwind working on a WHS2011 box?
And is it recommended to run it on software RAID1 within Windows?
Or might i better use CIFS to backup data from ESX vm to other (lowend) machine.