You will not get penalised for this. Despite what some people would have you believe, as long as cloaking is not used to unfairly gain an advantage in the search engines, this kind of cloaking is fine.
What you are suggesting *IS* using cloaking to unfairly gain an advantage.
It will get you better rankings, but not for long, as it annoys enough people like me that will complain to google about it. I rarely see these sorts of pages keeping their good rank for more than a month.