i have just a few of brief comments to give you some things to think about:
this probably won't cause any cloaking-related issues since the behavior is not based on user agent.
the googlebot won't store a cookie but it probably won't make multiple homepage url requests within 24 hours either.
not sure what the seo issues would be with multiple pages for a url request and it probably also depends on whether this is an internal rewrite or external redirect. if it is external you should also consider canonicalization issues.
There was a video on google by Matt Cutts replying to some questions. In it he said that if googlebot reads a page more than once, and every time it gets something different that this will raise suspicious.
One idea to avoid changing the content of the page is to present the different content in an IFrame, and once the user likes it store the cookie and present the formatted page. After all, robots don't store cookies (at least till today).
Of course this depends on how large is the different part. If it is too large IFrames won't be a practical solution.