First and foremost I would be curious to know if giving away beta version of your software would be a well thought out strategy for enterprise SaaS product. May be that is what makes sense for you and your team.
We designed our SaaS platform and started sales efforts right after it was tested thoroughly. We experimented with pricing and other variables. Our goal is to get first ten accounts and learn a lot during the process. Customer feedback is 'real' when you give them fully released product ( well, there is nothing like 'complete, fully released SaaS product', it keeps getting better in your software 'build management' process..)