I did finally "pull the trigger" and tried installing ROCKBOX with the utility. The good news I that I did eventually manage to use the utility to uninstall Rockbox and get the H2 to see the music on my microsd card. After the install I ejected it and when I rebooted it did a database update and the the interface was unchanged. It seems to still be the stock (1.7) firmware, except that now the player did not see anything on the "TF card", until I used to RB utility to remove "all" RB files. After rebooting into my old firmware I could once again see the music on my microsd card. The player is functional again, but a file named "rbutil-cache" remained on the card. I reconnected the player via usb and deleted this file, then ejected it again and rebooted the player. After several minutes updating music, the player seems back to normal, unchanged afaik, and still sees and plays my music files.
I've already, in another post, made a disclaimer that I don't know what I'm doing, but nevertheless thought I should post my experience, which might be useful for others. Maybe there is something I don't know about booting into Rockbox after the install. I would appreciate any relevant information from others and might even try again just to experiment. The stock firmware isn't terrible, but it's tedious to navigate even a relatively small, 64gb card of music files. I have bigger cards I hoped to use but have given up on that plan. Thanks for any feedback!