any cs/data sci/applied maths/stats/pure maths unsw/usyd vs uts course should have a sizeable difference in difficulty. while course names might seem similar, that's like saying integration is tested in 2u and 4u maths.
anyways, just from hearsay, the 1st yr uts maths courses are not comparable in difficulty and are much easier. also, i havent seen much representation if any from uts in quant trading.
just my 2c, but I doubt you would be challenged by maths courses at UTS given that you 99'd mx1 and 95'd mx2. there's probs a way to bsc double major or ditch honours to do a shorter degree if that's a concern.
i have also looked at past examinations from both uts and unsw (at least for first year courses, aka "mathematics 1" or similar) as well as complex analysis, and imo unsw seems to have some slightly harder questions, but overall its not a crazy super big difficulty difference; in first year both had some simple questions that were just computations, some harder questions, a small amount of matrix stuff. only noticable thing i saw is that unsw had a little bit more geometry with vectors than uts but thats not going to change the difficulty an insane amount. im not sure about later courses eg real analysis, but i really cannot say for the first year that unsw had immensly harder exams than uts.
in terms of representation from uts in quant trading, a simple search of linkedin for master of quantiative finance shows multiple senior positions and many quant roles at various respected companies, including commonwealth bank, anz, deloitte, and asx, just looking at the first few results. im not saying that unsw and usyd people dont have any quant roles but uts definetly has a very respected program with their masters in quantiative finance, which of course does trickle down into reputation from graduates from bachelor degrees.
honestly i cant really see the huge disadvantage from studying at uts, there seems to be ample opportunities, the commute is easy for me, the subjects and curriculum match my interests, no trimesters where curriculum is compressed, and from what i can tell equally challenging subjects to usyd and unsw. i do appreciate your input though, i wouldn't want to be in a position where im not being challenged or end up stuck after graduating, but from my research it just doesn't seem to be that way.