Well I hate to say it really, but I've had personal insight into the St Andrews-Manchester situation, whereby the St A students have done 3 years of lecture-based studies compared with the two years of PBL carried out by Manchester students...and it has to be said, the general concensus is that St Andrews students do know a lot more regarding pharmacology, physiology, and pretty much all the medical sciences.
This seems obvious, but the surprising part is that even in 3rd year PBL classes, students from St A only really have problems with adjusting to the different style of learning as opposed to clinical knowledge. Ok, I'm not a medic, I just know quite a lot of 3rd year medics at Manchester...
...and I'm also not disputing that PBL is more than sufficient for practising as a doctor upon qualification, but when the argument is over knowledge, I'm gonna go with traditionalism here I'm afraid.
As a disclaimer also, it depends on the learning capabilities of the students more so than the style of teaching.