I've really enjoyed the trackball in the center with my split Helix setup.
Switches: Sunsets (shout-out to lowprokb!)
Keycaps: MBK with printed LDSA thumbs because they're so comfy
Basic case designed and printed by me.
The keyboard looks very sleek and minimal, I love it!
How is your experience typing on that layout? Where is the space button? Where is return? Where is the scroll lock? ;-)
Also, how is your experience with a finger-operated right-handed trackball? I'm looking into getting a trackball again, probably finger-operated to minimise hurting my thumb, but I'm not sure if I want to go symmetrical or right or maybe left-handed (if that's even an option).
Having a trackball sitting between a split keyboard does sound like a great option. Right now I have my mouse in front of the keyboard and use it left-handed which helped with the RSI.
Thanks! Space is the 2U dark blue on the bottom on the left side (and one of the 1U dark blues on the right). Return is the bottom left grey key on the right side. Scroll lock is... Nonexistent since I never use it lol although I've been adding in a lot on my second layer so I could add that need be.
Finger operated right trackball in the middle has been very ergo for me, I used to have a symmetrical Kensington orbit which I liked well enough but it broke on me. I find tilting the trackball in the orientation of my arm works well enough to move my right hand between the right side and the middle.
I agree with your sentiment on thumb balls, I used to use one but found it worse for my hand overall and my thumb started hurting.