Birdie

Finds the Birdie meaningfully inferior to a GriGri: worse ergonomics without the index-finger loop, less smooth feeding and a non-progressive lowering handle.

Uses a Birdie outside all the time: slightly heavier than a GriGri but feeds more smoothly, more like an ATC, and has a metal handle.

Has used a friend's Birdie many times and doesn't love it: the flat handle is less ergonomic than a GriGri's, and it once jammed while lowering a climber.

Their Birdie works like a GriGri and is easy to understand, a bit smaller but heavier; paying out slack sometimes jams it for a second with thicker, stiffer ropes.

Likes their Birdie OK, especially the straight feed that reduces rope kinks, but defaults to the GriGri out of habit.