FYI... SR Follow does work with the RN3 (sort of).
I upgraded to RedNet Control v1.10 today, but ran into an issue with SR Follow feature. Automatic Sample Rate switching worked with JRiver until I selected a 192 file at which point automatic switching ceased. As a workaround, manually switching to 192 with RedNet Control or Dante Control would allow automatic switching to resume. I only tested switching between 44.1, 88.2, 96 and 192 files.
Louie, with US Focusrite Support, worked with me on this issue and was extremely helpful. A case has been opened to inform UK Support of this issue.
On a related note, after the v1.10 upgrade, if you repeatedly receive the following error when starting RedNet Control,
you will need to manually update the RN3 firmware to v3.7.2.
Contact Focusrite Support for the appropriate RedNet *.dnt firmware update file for your device.