They have a very different cut in the toebox. The masai is shaped narrow and low volume, with a very definite point to the toe. If you've ever climbed in an Evolv Pontas, they're very close to that shape. The heal has less volume (which i was looking for, everything has too much dead space for me) but the slingshot is much lower on the heel than any of my other shoes, by almost 1/2", and they rubbed a pressure point i have on my heel the wrong way and i'm now planning to return them.
The stonelands have a much wider toe area, with a kind of squared off shape to them, the polar opposite of the pointy masai shape. I found the heel and overall fit of the stonelands to be great, but the toe-shape did not focus the power for edging as much as i was used to. I only really tried climbing the lace version which has a very soft sole. I'm personally planning on trying these again in the velcro with stiffer sole next time i'm in the gym.
I just got a pair of tatankas 2 months ago. Havent had a chance to use them outside yet.. still winter here and been snowing a lot. But so far in the gym theyve excelled at what I want them to do.
They arent going to edge (they do edge quite well just not as great as say my Scarpa Vs ) as well as say the masai because of the less stiff midsole, but they absolutely crush it for toeing in on steep overhanging stuff.