So I did the straight BSci at Monash and attached Honours to it afterwards, which is in essence the same as the BSci - Research Advanced course. (I only did one unit different, which was SCI2010 vs. SCI2015 that I would’ve if I had completed the Research Advanced course, though SCI2015 is essentially the same unit as SCI2010, just one or two assessments changed and a more exclusive cohort.) I know of people who did the actual Research Adv course as well.
The main difference between normal BSci vs Research Advanced were the opportunities. In research advanced, Honours is attached and you’ll definitely get in depending in your marks. (Pretty sure you have to uphold a 70+ WAM to remain in the course, but then again, I did honours in 2018, so may not be the most updated.) There’s also a few other opportunities - networking, specific events for the cohort, an exclusive scholarship (I think?) and mentoring, which was harder to find on your own as a straight Sci student and generally more competitive. And then there’s the opportunity to do units early, though this can be a blessing and curse like it is to accelerate VCE subjects. (I did Japanese as my minor and accelerated those units, so I got a taste of that.)
Most students who do the course know that they want to do research for their careers but I have heard of some that were undecided and did it anyway. If you realise it’s not for you, there’s always the room to transfer courses - the BSci Research Adv course usually is the exact same as a normal BSci but with a few more compulsory units, so transfers are usually relatively hassle-free.