Dali Mentor 6 and Room Size

I’m planning a speaker upgrade and have decided on the Dali Mentor floorstander. I like the imaging and the design of the ribbon and soft dome drivers. My listening consists of 90% classical music.

My question is with a room which measures 12 x 16 x 8 ft. is the Mentor 6 the right size as far as bass performance or would the Mentor 5 be better suited? Mentor 6 has (2) 6.5” bass drivers, Mentor 5 only has (2) 5” drivers. I have auditoned in local HiFi shop, but they’re not available for loan.
Currently using PSB Synch Two’s with a Sunfire 300, ARC CD3 and the sound is big. Great soundstaging, but has that metal tweeter. BTW, my room is very well damped.

My question is not only limited to Dali owners...
not much info in the archives.
Really appreciate the response, Audiooracle.
I thought the Mentor 5 sounded light in the bass and I like the Mentor 6 with it's extra crossover at 800 Hz. As for the Helicon 400, $5500 is my budget and with a depth of 19", it's too large a footprint.

How does the Mentor 6 rate against the Synch Two as far as filling the room with a tight bottom end? Keep in mind I'm playing classical and the Synch's low end is excellent.
(As mentioned earlier room treatments are in place).

As both a Dali Dealer and a PSB dealer, I might be able to assist you.

Our demo room is very similar at 18 by 16 by 8 and the mentor 6 do fine, they are actually a tad bass shy compared to the Helicon's so your room size should be fine.

Personally I don't see this as being a big upgrade over the Syn 2 which are good speakers, I do think the Mentor 6 is a better speakers, I would just love to see you make a larger jump if you are going to swap speakers.