I know there is always a concern when a company wants to collect information about your computer and your use of their application. What exactly is being collected and what are they doing with it always come to my mind.
There is a thread on the PC forum that is discussing this exact point: https://forums.garmin.com/showthread.php?t=18985
I invite you to participate in that thread if you have concerns. I just want to say that we have done every thing we can to keep your data anonymous and the data is only to be used to enhance the user experience with desktop applications and the GPS. We have already used the data collected during this beta to improve Find and we decided to go ahead and move Fit support up, because of the high number of Edge 800 users that are using BaseCamp.
At the end of the Beta, you will be able to opt out of data collection, but if you want your favorite features to get more attention, you might consider opting in.