I worked on a (once) popular Saas app :) We were losing customers when I came in. But then started growing again (slowly) when we started shipping a bunch of great things.
But then the owner wanted to get rid of the "free trial" and was adamant we offer a free version. That would boost our growth to an incredible new level he promised. I could see the reasoning. Our free trial still required you give us a credit card up front. We just wouldn't charge you for 30 days. Asking for a credit card has to be bad for growth, right? People want to kick the tires before they become our customers, and there's a lot more of those folks.
So we ditched the collection of credit cards up front and went to a totally free plan. You could upgrade to a paid plan of course.
Growth started tanking again and we never got it back.
One theory was collecting the credit card just got the really eager shoppers and now our growth was from zombie, forgetful, monthly Saas payments. And that's valid of course. But I wonder too, if just asking for a credit card gets you to be more serious too about trying a product. If you have to put in a credit card, you'll probably focus in here for a bit and not sign up for 10 other things the same day to try. And successfully collecting a credit card while someone is in the process of choosing anything, is probably always going to be easier than trying to convince them in 30 days to come back and get into a buyers mindset again. Unless you really are selling something so deeply crippling not to have it again after 30 days.