Thank you for those fine details.
I've also noticed the ALZA tips in general give better mid-range definition - but it's really across the spectrum, not just the mid-range. If that model reduces Bass that would be unusual in the range, as well as enhancing the high's, it then thin's out the material - that's opposite to what the models I've tried so far exhibit, they thicken the overall presentation in some like the KZ S2's, but simply enhance the overall transmission through the tip as compared to the previous stock or 3rd party tips I've tried. The effect of isolation from outside noise may be part of the increase in small details and soundstage.
Thinning out can be due to a poor seal, you might try different sizes of those tips - one about and one below that size. For me it took a while, going from S to L, and all the sizes in between so see how each size affected the sound and noise isolation. For me the L or M of various brands worked best, varying by design and make - for the ALZA tips I've tried so far the Medium-Large or ML sit best in my ears. Not too tight, but a good solid seal to good effect on the sound and noise isolation.
The MTW2 are gone now, it would have been nice to try out other tips on them, I only used the stock tips before returning them - I didn't find them "special enough" and my time predated the fixing of the noise canceling. Perhaps the MTW3's will blossom like I'd hoped the MTW2's would, for $300+.
So far the ALZA tips I've used haven't failed to improve the IEM / TWS, except for the full sized ones not fitting in the TWS cases they sound great.
I'm listening to Picard (again) with the KZ S2's, quite nice.
Darn, even the short ALZA tips keep the KZ S2 case from closing... I pulled the ALZA tips and moved them to the 2nd pair of KZ S2's for another 4 hours or so...