My recollection of my brief time w/ the XM3 is they inserted similar to what I get with the Airpod Pros, what I'd call a medium'esque insertion. That said, the AP might be a better fit for my ear as they lock tightly against my concha like a good CIEM, that I don't recall getting w/ the XM3.
The difference is more likely the quality of the seal - the Airpods are vented.
https://www.apple.com/airpods-pro/specs/
"Vent system for pressure equalization"
I really like the Pro. I'm impressed with the ANC, and it's got to be better than the XM3 ANC. One thing I notice is that ANC on Pro depends on seal. Like for example, large tips fit me the best, and if I use small tips, the ANC isn't as effective. Apple surprised me how good their ANC tech would be.
Also, there seems to be come mixed opinions on the SQ of these. I think the issue could be the adaptive EQ. Looks like the way the EQ adapts is based on the acoustic sensors around the housing(which is likely effected depending on ear shape). Which is why my earlier measurement looked so bass heavy. If I seal off those acoutic sensor points, the bass levels down. This explains why the measurement and what I heard was different.
I do very much like the convenience of these with the squeezable click button. Really easy to go on transparency mode. The ANC is very useful in noisy situations when listening to music or talking on the phone, drowns out majority of the low-end noise. It seems very effective and performs quite well. ANC is very practical for pro, as a device for on the go. I was quite surprised how much of a difference it makes at the gym with ANC on.
In terms of microphone tonal quality, from what I've heard of the recordings from the reviews, it could be better. I've had people tell me they hear odd signal issues. Mixed result so far. From what I hear during phone conversations, wired mic perform better than these directional mics on wireless headphones/iems.
Signal quality on the other hand is supurb. I've tested what would happen if I have my phone if I sandwich it in my pocket on the exercise mat, covering with my body. Interestingly, the signal didn't cut off. With the Jabra 65t, I've had signal issues with this. Also, the signal is very stable over long distances as well.
Ok, the price is higher than most TW out there, but it has additionial practical features (including ANC which majority lack), and works seamlessly. Pro is definitely a keeper. It's not a wired iem, and I know I can get better sound (interms of resolution etc.), and I don't expect that level from wireless using AAC. It has no nasty peaks or overbearing bass, and therefore pretty balanced sounding, and I'm good with that. No issues with making out sounds clearly either, and for it's intended purposes, it works well.