Hiya, as a second year in biomed ill give you some insight.
It is important to understand that both biomed and science are vigorous degrees, and saying "biomed is harder than science" is not entirely true.
The pros for science is; yes alot more flexibility, and thus picking subjects that you can do fairly well in will be your advantage, however it is a larger cohort so you may (at least in 1 year) not be around ppl with the same ambitions as you.
In contrast, biomed in your first year you will have six compulsory subjects in your first year, (which only leaves you 2 breadths), the biomed subjects are more intensive than science; i.e. biomed has chem for biomed in 1 sem whereas science will have chem 1 and chem 2 (which they do in a year, although science students can do the biomed version if they want) and the same is applied in physics (however we focus more on biophysics), they try to shove all the content into a semester, whereas science you will get to do the content in a year.
However, the biomed cohort is smaller and therefore you will be able to make friendships and networks more easily.
Since med ha removed prerequisites you do not necessarily need to do biomed, however, your second-year core subjects are rich in content (and although challenging) will provide you a more integrated understanding of your knowledge of the human body, which science does not get to experience.
As for 70+ results, it depends on a subject but typically a 75 is a very high (and credible) mark, so as long as you work hard a 70+ is doable, and even if you trip up in your first year, your second and third year are worth more in your gpa calculation so you can redeem yourself as you become a better uni student. This is the case for both biomed and science.
I think its fair to say biomed is tougher but defs rewarding.
When it comes to deciding its important to know you can always transfer if you don't like ur first course, we had plenty of science students transfer into biomed midsemester and vica versa.
So I can't tell you which degree to choose, because both are great and will provide you an equal chance into getting into post grad medicine. I would encourage you to do your own research in the beneifts of each course and consult your career counsellor.
Personally, although biomed is challenging I have no regrets and have been enjoying it (but the same can be said for science) either way both are great!