Hi Anamoroto,
You have been asking essentially the same question for many weeks now, on this and at least one other forum. No-one can make this decision for you, it's going to be your call.
It seems to me from your past questions you are concerned about how long it will take for you to get your degree, and also which is the more difficult (rather, which is the easiest path) for you to follow. In my opinion, I think this is the wrong way to go about it.
You have a confirmed spot at one of the best medical schools in Australia. If you waited until 2008 for a graduate entry two things will happen: 1) You need to apply through a process that, although similar, is different to undergraduate entry. There are no guarantees you will do as well, or will get an offer from a school as good as UNSW. 2) The total amount of time it will take you to get your degree will only be 6 months less (from what you say about UNSW giving you credit).
So on the face of it, you are gambling a spot at UNSW for the possibility of gaining entry into a school (potentially less prestigious) that will give you a degree 6 months earlier.
I know what I would do.