I use my moonlander with the thumb clusters pushed all the way up instead of down or 'tented'. However this created some wobble so I bought an extra set of feet from ZSA and installed them on the outside of my board (there's already a screw hole there from factory, just need to take the cover off). I love it! I have small women's hands and no problems at all with my moonlander layout , cluster buttons set to my modifiers and space bar.

If you'll forgive my filthy desk picture, here she is:

I've got a moonlander, and pretty average-to-small hands, I guess. I can comfortably use 2 of the thumb keys on each side. I have to move my hands off of home row to hit the third keys, or the red keys comfortably. I've bound those to functionality that isn't typing related, and that works well for me.

I find the Moonlander thumb cluster not that easy to reach. I have medium/large hands but relatively inflexible thumbs and use only 2 of the thumb keys. (And one of the bottom row keys as a third thumb key. If you do it that way it is probably not much different than the Iris). Personally, I would like the thumb cluster to be closer to the other keys and/or splayed.

Have you tried: https://jhelvy.shinyapps.io/splitkbcompare/ to see if the size is right?

I have pretty small hands and found the moonlander way too big. Moved to a skeletyl fromm there. If you need more Keys, have a Look at the sofle v2, which has a more aggressive pinky stagger. Or the keyria.

I think it's pretty easy to assign rare operations to the more unreachable parts of the thumb cluster and be fine.

I find that even with my pretty large hands some of the bigger reaches, like left shift to the rightmost column of keys on the left side, can be a bit cumbersome.

Personally I could never find my groove with the moonlander. I used it for about three weeks and couldn't overcome about a 30% reduction in my wpm. Worse though was that I could never get programming to feel really good on it. I acknowledge this has much more to do with me being an old dog that's opposed to new tricks, so I was probably just doing it wrong.

My moonlander has been collecting dust in its box for about three months, which I find to be a shame. Maybe I'll break it out and give it another try.