I just finished my first year of the B-Bus/B-Sci(IT) course. The odds of transferring to the double degree if u just get into IT all depends on how well you perform in your first year (and they may consider a transfer after semester 1 if you're doing really well). however, im no expert on this subject, so i'd give uts a call early next yr to find out exactly how transfers work.
The IT component of my degree is decent, and gives four key options for majors that you must choose one of.
Enterprise Systems Development
Applications and Internetworking
Data Structures and Algorithms
And theres a 4th one to do with business systems, i cant remember the name
The only good subject in first year IT is programming fundamentals (if you're into programming that is). The others are pretty dry and are just introductory. But thats gonna be the same anywhere.
After a quick search of the UAC website, the cutoff for the double degree was 88.2
and the cutoff for the single IT degree was 82.5. I would strongly suggest that you try and get into the double degree, as having both business and IT knowledge will open up many more doors for you in the future. Having said that, dont do the business degree for the sake of it. if you dont enjoy business, your not gonna like this. and although business studies, economics or commerce will help you, they arent absolutely necessary. however, hard work is required, and the first year subjects (accounting, management, marketing and economics) are no mere walk in the park if u wanna do really well.
Here is the link to the UTS handbook for the IT degree
http://handbook.uts.edu.au/courses/c10152.html
and here is the link for the double degree
http://handbook.uts.edu.au/courses/c10219.html
Overall, I can highly recommend UTS. The people are nice, the facilities are pretty good (IT building is probably the nicest of them all). I was hoping to get into sydney uni when i applied last year, and was pretty apprehensive about going to UTS when i got my offer. but after being there for a year, i wouldnt wanna be anywhere else.
Good Luck