Daddymax,
There are a lot of factors to consider here. I think whether or not the URL would fall out of the SERPs would depend on what kind of redirect you use. For example the 302 signals a temporary redirect so Google may not strip those out of the SERP?s although I have no direct experience with this.
I have moved websites using a 301 redirect and old domains typically fall out of the SERPs after 2-3 months. Even though that is true, I typically strip content from old sites to be used on new domains and the old URLs simply serve as work horses to flow traffic to a new domain. I?m assuming in your case you will leave content on your site?
All that being said, if you plan on using the domain and content again after this deal is through, I would reconsider saying yes. If you do redirect your site for a short period of time and URL?s do fall out of SERP?s, you can?t just switch back to making money again. You will likely lose all of your rankings. It may be as if that other domain sucked all the life out of yours and then left it for dead.
Again I?m not sure if this would happen but if you plan on using the site after its over, you might not want to do it.
Best,
Shawn