If what I read is correct the smaller mbl speakers share the same top end as the 101E's but with a smaller bass unit- Instead of going with the expensive 101's could you use a smaller unit and match it to my JL big GOTHAM- my room is 17x27- would this ineffectgive me the same as going with the 101's???
Those lamellas look pretty hard to drive - and I imagine they have to be heavily damped somehow to prevent internal vibrations (a lamella is like a guitar string just much thicker but anything long and narrow and flexible is sure to vibrate) - so be very careful - I am not sure there is a free lunch here as surely MBL would have thought of this if it were possible.

I'd hazard a guess that the limitation is in the output of the midrange of the lamellas and not the bass woofers. This is of course speculation on my part so you would probably be best to contact MBL.
MBL has thought of this and offers their own sub. I've heard the MBL sat/sub
combo and it sounded very good to my ears, although the dealer doing the
demo absolutely preferred the small mbl floorstanders (116?) at app the
same $. I think I probably liked the sat/sub combo better. Since YMMV, you
should probably try to A-B these 2 alternatives before you settle. You could
also use their small floorstander with a sub, but I've never heard that combo.

As to a 101 comparison, the tonal balance is different (more mid/upper-bass
on the 101) from the sat/sub. The 101 needs a very large room and, for
your purposes, it's hard to say whether the 101 or the sat/sub would be a better
fit in your room.

Good Luck

Klk, I've had the same thought, and will likely walk down that path in the near future. I just recevied my MBL 121 monitors and like them a lot, even without any help from subs, but it does feel like it's a natural upgrade path for me to add subs, and I'll be adding the JL Audio ones. Will likely get two 112s. My first upgrade needs to be a new amp though, as I'm a bit between amps just now.
Klk nice sub but the answer to your qustion is no.
I A-B compare the MBL 121 vs MBL111B. No contest here - 111B wins big time. Without the sub they sound very similar. The Sub of 111B is similar to that of 101e and it's the size of a small fridge with 12" woofer goes down to 20Hz and with 30mm MDF and internally braced for extra strong construction. Even with large volume bass the sub didn't vibrate.

If you pair the 121 with another brand's sub make sure they blend well with it because not many sub out there are manufactured to the quality like MBL's. Personally I think the natural upgrade is to sell the 121 and get a 111 or 101.