Hey Stephan,

I'm assuming you want to measure how the traffic is converting on the new site, hence the strategy to send small portions of traffic to new pages?

If so, the easiest way might to just straight up A/B split test the new pages with a service like Adobe/Omniture Test&Target. This doesn't cause any cloaking/dupe isseues. When you are happy with the results you can realese the site with all the 301's in place.