There really is no downside or risk. While you're in BizSpark, you'll also get $150 / month of Azure usage which can be used for production hosting. Normal MSDN Azure usage is for dev/test only.
Only downside is that you cannot have web development as your main business. Kind of fine terms when thinking about it. You get access to pretty much anything from Microsoft to use for your development. I have been very happy about the BizSpark program so far.