The results you get have a lot to do with the particular setup of the system.
I worked for close to 16 years at SBS. I sold and set up the JM Labs many times. The results you could get out of them had a lot to do with what you were running them with.
I was the detail setup freak so when I demoed the speakers for my customers I made sure they heard the systems set up the best way possible, on many an occassion the setups were not optimal and the system didn't sound great.
The BE versions of the JM Labs do a lot of things well. The BE tweeter is way smoother than the earlier non be series, also the midrange was more integrated and coherent.
I will agree with Sir speedy that the JM Labs bass is loose.
JM tunes for a big presentation and a tighter more accurate bass is well less French. The problem with the JM Labs is that the baffles are too big and they present a big but not super well focused soundstage.
I will agree that a REL or any other really good subwoofer will dramatically improve a speaker system. Even the big Wilson's at SBS improved dramatically with a good sub.
I have on display in my showrooms the new JL Audio Fathoms and they improve all the speakers I play them with.
It all comes down to taste. There are ported speakers with great bass, speed and slam and sealed ones which trade bass depth with volume.