We are releasing our first b2b beta in Q2 of 2014 and would love feedback on what works to get active beta users using our new product.
I encourage you to read some answers of mine to similar questions asked on Clarity below.
The value of Direct Outreach: https://clarity.fm/a/2149
Understanding your customer acquisition costs: https://clarity.fm/a/611
Using Twitter for early outreach: https://clarity.fm/a/438
The most important thing to do is to qualify your users to ensure that they really are the people that really feel the pain for the problem you are solving. Offering them early access in exchange for a quick survey is a tactic I've used with pretty good conversion.
Happy to help talk through the specifics of your path forward in a quick call.