I have the Ergodox EZ, so similar to the Moonlander. It took me about a full workweek to use it without looking at the keyboard, and another week to type at a competent speed. That said, after three years of ownership, I still can't type as fast as I can on my MacBook's keyboard (last I checked: 65wpm with the Ergodox, 109wpm with the MacBook).
Moonlander user here -- sort of, but not really. One of the reasons I bought it was the non-staggered keys, and I'd say it met my expectations. All the keys off the home row just seem a little closer.
I had been using the Kinesis Advantage 2 and for me there was almost no adjustment time. It did take me quite a while (two weeks) to get used to the Kinesis.
Still totally worth it.