I'm curious how this goes (so please post a write-up when you have data). We (www.agentmethods.com) collect credit cards up front exactly to avoid that "create the account and forget about it" situation. The clock is ticking so our trials are serious.

We experimented with removing the credit card at signup and it killed our conversion rate from trial to happy paying customer.

We now invest a significant amount of support resources into trial users which we wouldn't be able to do if we opened the floodgates to every uncommitted tire kicker.