For reasons I don't understand, ortholinear is either a Really Big Deal or it just... isn't. I'm the latter. Switching to the ErgoDox layout took some doing, it's been an iterative process of tweaking the layout, but actually typing on linear keys was a transition I barely noticed.
For different brains it's a complete showstopper and they have to learn how to type again, for many people that won't be worth it. I prefer typing on linear keyboards.
There is unfortunately little way to tell which camp you're in without trying for yourself.
Ortholinear is just a straight grid of buttons. Columnar is what most split ergo boards are. Having used one I don't find ortholinear very good feeling without a split, as it makes your wrists go in a weird angle.
I sorta transitioned in via way of an ortholinear which I think helped a bunch. Rather then going from a normal board to a splitergo, I used a preonic for a few months first. I have let others use my split board, and I've seen what you're talking about. Some people are able to adjust pretty easily, others just panic. The harder part is all the weird thumb buttons they have to use (backspace, enter, and [] are all thumb buttons for me)
For any one worrying you lose skill in other layouts when you switch, I haven't found that to be the case. For the most part I can transition back to a laptop keyboard pretty easily and only attempt to hit certain buttons that aren't there once or twice in the first few minutes.
