Oh wow! Great thread, thanks for keeping track of all of this stuff.
I've been playing around with INit, but after some initial promise, I haven't seen much in the way of upgrades, or at the very least, any talk on the developer's thread here on ENWorld. It really just needs a draggable edit mode that dynamically updates a character's initiative as you drag, and perhaps two checkboxes for readying or delaying actions and it'd be a perfect solution for almost ANY game system, for a DM or a player that just wants to help stay on top of the initiative order.
I just downloaded DM Tracker, however, and it's absolutely fantastic--most of my wishlist for INit is somehow addressed in the app which is great. It's a bit of a different animal in its usage perhaps (at least in how I envision using it) simply because it's more geared towards DMs.
After five minutes of playing with DM Tracker, I'm not sure how it would handle readying or holding an action, so that might be something for the developer to think about for a future upgrade, if he/she is following the thread.
But overall..... Big thumbs up for DM Tracker here!
I'm very curious to take a look at both of the character tracking apps once they're both approved.