I recently landed a few beta user's for Gaffer (gaffer.sh) and they've been super insightful.
In the past, I was tentative to even communicate with beta users because I figured I'd bother them or scare them off. Part of working on Gaffer is that I wanted to avoid past bad habits and get over fears this time around. I sent out a couple quick emails like "Hey, thanks so much, how'd you hear about Gaffer? Are you liking it so far? Anything I could do to improve your experience?" and of course they were happy to respond and give me feedback.
One of the beta customers pointed out that they nearly didn't sign up because of the lack of real explanation of the main landing page. They were even nice enough to send over a list of tips that helped with their own product.
Long story short; get over the fear of reaching out to customers. Two or three simple (and surprisingly pleasant) conversations gave me exact answers and problems to solve.