Captive caps were a much-needed upgrade to the Iceflask and make them much easier to use. It's a feature that they should have had from the beginning. I'm glad to see that all new purchases will come standard with them and despite some grumbling, I do genuinely appreciate the opportunity to purchase the upgrade.
The captive function is really helpful. It makes the Iceflasks significantly easier to use in the field. No more having to juggle the removed cap. On that front I have no complaints.
But the cap itself is actually worse than the original. The cap portion isn't as tall as the non-captive version. I find it's much harder to grab and unscrew then the original. This is fine in ideal settings, but a little frustrating when your hands are wet, dirty, muddy, bloody, or it's just cold. A version that's a little higher profile that still keeps the cap captive would be a big improvement. There's space to spare on the Iceflask, there's no reason why it shouldn't be easier to grab.
I will also note that the tethered cap has doubled in price since my initial purchase in mid-March. I don't think they're worth the current price, especially when you factor in the cost of shipping. If I were ordering now I would feel ripped off.