@rischa - I bought my JBL 4349’s two years ago. I read extensively about these speakers before I bought them as you are probably doing.
I’d recommend simply to just listen to them and put away all the reviews, graphs, etc. I very much enjoy my 4349’s. Yeah, probably not an "audiophile" grade speaker in many people’s minds (a good friend has asked me why I have a pro audio "PA in my living room"), but I’ve had two years of really enjoyable listening. They will play at whisper quiet levels with much detail yet play at very high volumes that can be great fun. I too wondered about the dip in response that was noted in reviews, but that has not been noticeable by me or others that have heard the system in detail.