Choosing between stable and development snapshot releases for a new high trafficked site
It's a difficult question to answer, because the status of a release (dev, beta, RC) is not necessarily a measure of it's stability, but rather an indication how well it has been tested before the maintainer released it. A module's dev version can (but does not need to be) more stable than the latest beta, RC or stable release.

IMHO, 200 is a huge amount of modules. If it's an option, consider reducing the number of modules. Often, 80% of a site's functionality is created with 20% of the modules, so the question is if the last 20% of functionality justifies the other 80% of modules.