Agreed that people seem to emphasize and boast about MCAT more than research.
I'd say: more important than being on X+1 projects, make sure you know what you're talking about when someone asks about your work. If your name is on something and you want credit for it, you can't say "I did this" without being able to succinctly answer what others contributed, and why it's all important. Better still: how is it helping now, and who is using your results?
If you can confidently answer (or evade) those questions using your current experience -- essentially, if you're proud of what you've contributed to the projects -- focus on the MCAT. As it stands, your research experience seems more abundant than many others, so acing the MCAT seems a lot more important than another poster or a chance shot at a publication from the experience many months (or a year) down the road.