One KEY feature Rockbox has over the original firmware is the ability to add folders, albums, artists, songs, etc. to your now playing playlist on the fly (Just long press on the selected album, and click "current playlist" and "insert last"). The original firmware only lets you add songs to a playlist one song at a time on the device, but I tend to mostly listen to full albums at a time and set up a playlist of a few albums and then just let them play through. And I know I could create a playlist on my computer first and copy it onto the original firmware, but that's way more work, and I like to be able to turn the player on, decide what I want to listen to in that moment, and make a playlist full of a bunch of albums without having to touch the player again to change albums.
I use bluetooth headphones occasionally, but I much prefer analog headphones, especially for high resolution music that this player supports. My favorite headphones are the Tunai Drum (more bassy version) and Piano (more balanced version) earbuds. That said, I actually use the original firmware more for high res files since Rockbox actually downsamples anything higher than 44.1khz/16bit down to 44.1/16, while the original firmware supports 192khz/24bit and even supports surround sound.
So the way I use my Rocker mostly is, if I'm going to be listening to a bunch of different albums by a bunch of different artists and I want to quickly set up a playlist of them to play in order, I'll boot up Rockbox with a 200GB SD card that has my larger music library, consisting of mostly mp3s (320kbps when possible). But if I want to listen to a single high resolution album, I'll put in a different 200GB SD card that has all my high-res FLACs on it (a smaller selection, but some of my favorite albums), and boot up the original firmware, and listen to that album at the best quality.
For me, battery life isn't an issue. I use it mostly on my 1.5 hour commute, and charge it at home and at my office. Since I rarely use it until the battery runs out, I don't even notice the battery life difference between the original firmware and Rockbox.
I came from using a Sansa Clip Zip with Rockbox for years, and had wanted a more high-res player. I got what I wanted with the Rocker's original firmware, but was missing Rockbox's easy playlist features, which I was happy to have back once Rockbox released for the Rocker.
