I have a brand new (actually 2 brand new) Ultra that is intermittently having the choppy/stuttering sound issues. The first model was ~2 months old and was doing it, and I had to end up replacing it through Amazon bc it would not pair with the remote after Roku support walking me through every possible option. The new one has been installed prob 2 wks, and it is now stuttering - but the remote pairs and works fine.
I'm with other posters that Roku has some combo of software/firmware/hardware issues they need to work out. I work in the high tech space and we mfr swr + hardware and I know how complex this is but you have to figure it out. I hate Apple in general, and their older gen AppleTV device and remote, which I have three of and replaced with Rokus. But Apple has never ever had the number of odd issues I've had with Roku devices.
Can you please provide more information about the issue you are experiencing? Is this issue occurring on a specific channel or does it happen on all channels? What OS is your Roku device running (this can be found in Settings > System > About).
With more information we will be able to assist you further.