Hi Sumanta
A cabinet for a full range is a lot more difficult to implement than a OB.
A well designed full ranger sounds very good.
I have owned a OB in the past.
Audio Artistry Beethoven loudspeaker system | Stereophile.com
Its probably one of the finest OB speakers designed.
At present i have the Rethm Saadhanas which are better in some respects over the OB, especially in terms of coherence, immediacy and micro dynamics whereas the OB had more scale and better bass but thats natural since there were four 12 inch drivers.
Now I wonder how wonderful Rethm Sadhans are! I was in Mumbai last week for just a night, but still feel sad to loose an opportunity to listen to such speakers.
Those Beethovens are truly wonderful in looks. And you already informed their performance.
The very first two reasons for me to go for OB was the ease and economy of having OB speakers.