If it were me, I'd try a few hundred rounds of some different defensive 9mm ammunition, and then I'd make my selection from among the ammunition that exhibited acceptable feeding & functioning in my pistol ...
I'd be more concerned about proper maintenance requirements; ammunition tolerance/reliability; and preventing any shooter-related functioning issues from occuring in a diminutive polymer framed 9mm ...
As far as the actual performance differences between the SXT and the L/E SXT-derived T-Series, while both share the reverse taper jacket design, the nose cavities are different in shape and jacketed coverage, as well as the actual notching design, with the T-series having the jacket petals which fold over the cavity edge, protecting the expanding/deforming lead ingot's leading edges, and controlling the expansion ... and not to mention that the jacket petals can potentially fold over/outward in a manner which makes them a potential cutting mechanism. Then there's the other differences besides the actual bullets themselves, as hotpig mentioned.
Hotpig may be able to offer some better information, considering his connections, but last time I asked a W-W L/E rep for some 'gel/barrier performance data' on the commercial handgun ammunition, he said they didn't commonly do much testing intended for public release except for the L/E ammunition lines, since their L/E customers obviously desired the information when making a selection of service ammunition.
Now, I've seen some in-house gel testing info developed from some 2002 testing on some .38 Special, intended for L/E customers desiring performance data for .38 Spl ammunition, and the rep said they obviously tested loads during development.
He told me their new .45 ACP 185gr STHP was still intended to be a 'reduced penetration' bullet design ... which is why they didn't really market it to L/E as service ammunition ... and told me how their in-house testing revealed the expected expansion & penetration of the bullet. He found a single box of it in his trailer and fired a round into the gel block we were using for other testing, and lo & behold, it expanded and penetrated to damn near the exact performance he'd mentioned.
They obviously test, but they don't necessarily advertise the 'performance' of the commercial designs. Maybe it's a PC thing. They were stung in the media rather badly by the Black Talon episode, you know ...
