It looks like the creators of Spin Rewriter 9 .0 have really put a lot of work into creating a piece of software that creates readable content. However, Google isn’t stupid and there are a lot of things that can go wrong when you are trying to “manipulate” Google into giving you more traffic. Google hates spam, badly written content and duplicate content. These are all things that Spin Rewriter 9 .0 is capable of creating. You simply can’t trust a piece of software to write content for you in my opinion.
Imo it is not possible for google to detect properly spun content, it is not worth computing power it requires. They can do this using ngrams for example, but it is uses a lot of queries. And for example article spinner I coded beats this algo, so google cant detect that the content is spun. Manual spinning is also good but it takes more than 30 minutes per article. 

Spin Rewriter 9 rewrites content on paragraph, word and sentence level. It also turns sentences around and makes sure that only appropriate synonyms are used. Aaron added a special ARTICLE GENERATING ALGORITHM to Spin Rewriter 9.0. This algorithm makes sure that the generated articles are even more unique, and even more readable — if that was even possible!

"As an Internet Marketer I always need unique contents for my sites. SpinnerChief has really impressed me from the quality and unique content it provides. The most powerful thing is I get as much unique articles I want with only some clicks. If you want to rank your sites high then you really need this because search engines love quality and unique contents. I can't recommend it enough."

There are some 'free' article spinners out there that require you to enter your text with properly formatted 'spintax' in order to create the end result. But how you need a totally separate tool to create this machine formatted text, so how is this really useful to you? Spinbot does all thinking for you, from taking in the context of every phrase to creating additional textual content that is as readable and meaningful as the text you originally entered.