It's definitely a decision that can go either way. For each of your points, there is a different perspective that many IM distance triathletes are good with:
- I never use the touchscreen while training with my Ultra. Pause is a button press and the Digital Crown goes through the screens.
- I swam with both an Epix Pro and an Ultra 2 for about 4 months this year. My Epix Pro was wrong more frequently than my AW (as in, I truly did the math and the Epix got distance wrong marginally more than the ultra). I also just want to swim and get it done, I don't want a drill mode or whatever. I don't want to press any buttons when I am swimming. I just want to get the workout done to plan and crush it.
- I have zero devices that use Ant+ only, all reasonably modern bike PMs use Bluetooth as well
- I have yet to have a day where I outlasted my ultra - just had a 4 hour bike + 40 min brick run a couple weekends ago, ultra started with 78% battery, no low power mode at all, screen on the whole time, streamed music while running... it lasted fine.. charged it for :30 min after and never thought about it again.
That all said, if someone wants a watch that 'just gets it done' - yes, I'd go Garmin too. But if you want to use your Apple Watch Ultra for IM training... you absolutely can and there are no enormous sacrifices.. but there are LOTS of extras that Garmin can't match (you might not care though!)