I’ve been using a Sofle split for almost a year, probably in about 30-40% of my typing. Despite tweaking my setup as best I can, I still find the experience difficult.
One issue that seems to have a big effect is that I still think of the position of mouse in my dominant hand and keyboard with my other hand as useful.
I use it often for everything from casual surfing to editing. For example during editing you’re often selecting text with the mouse and doing some minor editing with your other hand. Split keyboards seem to really remove this efficient option since both your hands need to be used most times.
A lot of people who extol the benefits of split keyboards are comparing to traditional keyboards when your tasks are static.
Form and function are inextricably linked: one will inform the other. A lot of the ergo-split community focuses on the use case where you move your hands as little as possible, and the designs tend to revolve around maximizing that ideal. And they are damn good at it. The drawback, as you note, is that it’s a design that expects you not to move your hands around: it encourages keyboard navigation and shortcuts in place of using the mouse as much as possible.
That said, you can get around it. You can use layers to move common shortcuts to the left hand, so you don’t have to do the whole “Stretch my hand across two units” dance. Or, you can look into something like a macro pad.
Me, I just deal. The comfort when typing is well worth the tradeoff, to me. I’ll favor avoiding the mouse when possible, and just dance my one hand across both halves when needed. It’s not a huge deal to me, but the whole point is personalization: find what works best for you!