Having come from other Spinfits like CP100+ & CP145 and the Springtips, I can definitely notice and appreciate the added comfort, seal, security and the fit on these. First, since my ears are of different shapes from each other, there was always a fit issue that I experienced with all silicone tips, losing significant amount of bass in at least one ear. With these, I am happy to say that's not the case anymore! Also all the other spinfits have become loose but, with the way grippier core design in these, I hope that's not the case🤞 . Important note: I have noticed more condensation in my ears after I have started using these, which must be due to the snug fit.
Now coming to the sonic differences, I have only tried it on my S12s. I have noticed more sub-bass as stated above, slightly forward vocals, less mid-bass, less lower treble and more upper treble. Basically, at least to my ears, it turns my S12s from a V to a W, but more close to a U. Which I don't mind as much, as I am quite sensitive to the 2k-3.5k range that it affects, which also might have something to do with the perceived slightly larger soundstage, although I do miss some of the thick mids however slight EQ magic fixes that particular concern.
Overall I am quite happy with these eartips purchase. At the very least, it offers some significant sonic differences (or upgrades, depending on how you look at it) while also offering all the benefits of upgrading to a premium product.