There's a whole lot more to an application than the GPA; there are definitely people with that GPA that get into med school, but it all depends on the other stuff. Do really well on your MCAT and I (personally) don't know if you'll need to do a postbacc. I would not consider St. George's. If you get over a 30 on your MCAT, you don't need to. Maybe you should go and talk to your premed advisor about it. My advisor was very helpful, told me that I was on the border of being accepteptable, but if I did one of these post-baccs (and did well), I would easily get in. If that is your situation, then look at the various post-baccs.
There is also more than just georgetown; there is also drexel, finch, loyola-chicago, nymed, and probably a couple more. $30k for a year is a lot of money though. I'm currently doing the SMP at Georgetown and it's great. It's a lot of work, but it's definitely manageable. They recommend at least 5 hours of studying a day, and I think that's a pretty realistic number.
Since our grades are based on the med students curve, no one in the program is competing with each other. In the grad school classes, the grades are not curved. Everyone wants to do well, but it's a very friendly atmosphere and people are always willing to help each other out. That has been my experience, at least; there is always going to be someone who is extremely competitive. Overall, it's a very worthwhile experience, and next year is going to be extremely easy (comparatively) for me, no matter where I end up.
I think you will have a good shot of getting into the SMP, as long as you apply early. Avgs are usually about 3.3 and 30, but the difficulty of getting in changes immensely as time goes on. Apply early with decent stats and you'll get in easily. Later on, people with good GPAs and MCATs, who for some reason or other get rejected from med schools, panic and apply to Gtown, so then you're competing with people who have 34s on the MCAT.
As for being in class with the med students...it's just that...i dunno, nothing special. I think at some other schools you have to watch the lecture on a TV separate from the med students, and I don't know if I'd like that too much. Here you are treated just like a med student by the professors and the faculty, you are not any less important. The faculty of the SMP are amazing though, they really care about the students and want us to do well. If anything, we get much more attention than the med students.
I think you should apply to med school the summer before you enter the program and do as many secondaries before it starts. Yes, it's a pain to do it during classes, but it's a whole lot better than waiting an extra year. Georgetown sends periodic grade reports to your med schools, so you might get in later than people not in a masters program, but you will get in (as long as you don't fail your classes). And hell, if you don't get in, you haven't lost any time. Just apply again, this time with all your grades. Alright, this has gotten really long; if you have any more questions, PM me and i'll be happy to answer them.