SysKit is actually the name of the company, not a product. Formerly Acceleratio, I've used and evaluated SysKit products throughout years for a variety of purposes. In my organization specifically, I use SPDocKit the most often in my line of work. SPDocKit is an excellent tool for documenting SharePoint farm configurations and settings, both for informational purposes as well as more formal D&R preparedness needs. I've been using the product since it was first offered years ago, and there is no other product that does what it does as well as it does on the market currently.