I don't know the exact pros and cons of each but I have heard that systems based makes it a lot easier to learn esp. for the boards. Also, most if not all schools in TX have converted to systems based learning. I just interviewed as WVSOM and they had both PBL and Systems but now they got rid of PBL. So I guess it's a new trend or something? I am not choosing a school soley based on this curriculum but it is one of the biggest determining factors.
After going to several interviews and learning about both methods, Systems based (especially the style at KCUMB) is extremely appealing. It just makes sense bringing all medical peripheries into a system and learning them all at the same time. I personally don't learn very well taking unrelated courses that do not integrate within an overall topic. Curriculum (along with rotation sites) is EVERYTHING in a school. Find the one that appeals to you.