To CC upfront, or not to CC upfront, that is the question

I launched Tatask (hierarchical task management) just under 1 month ago requiring a credit card upfront to access a free trial.

So far I have 3 paying users but have seen quite a few users sign up and then give up when redirected to stripe.

I have removed the need for a credit card on sign up today but I don't know if it's a good idea or not?

Does anyone out there have experience having tried both alternatives?

I am curious what your best practices are for encouraging users to upgrade and add their credit card at the end of a free trial?