Yellow Ink stem in a Black Ink housing makes for the same switch, just a little heavier. *Nope - totally wrong about that; they actuate when you breathe on them. Closer to being accurate with Ink Blues, though.
Here’s a comparison between some stems; Ink Yellow, Ink Black, Halo True:
Each is lined-up by the top so you can compare the other dimensions relative to that. The Ink Black stem in the middle is the most typical; with the contact legs extending slightly past the “feet” where the switch bottoms-out. (There’s more space for the contact legs; they don’t touch anything besides the leaf.)
The Ink Yellow stem has the “feet” extend down to the same depth as the legs, so it bottoms-out sooner than but in the same way as a typical stem.
The Halo stem has an extra-long center post, similar to Kailh Pros or Creams. In most housings, that center post is what hits the housing, making the distinctive “tak tak” sound.
The down-side of this for me, though, is that the stem teeters on that single contact-point when the switch is at the bottom. For me, this lends a slightly unstable feeling to the switch - not so with the Ink Yellow (and presumably Gateron’s other shrouded-style) stems.