The Power amplifier in Beocenter says system frequency range 70 - 20,000 Hz and in Beocenter 9500 20 - 20.000 Hz. Is there no deep bass on the Beocenter 9300? 

It will be a typo - the power amplifier is the one bit that didn't change! The rest of the 9300 is pure Ouverture.

Both here on the Beoworld product page and in B & O brochures it says 70 - 20.000 Hz for Beocenter 9300 !?

As Peter says, it's a typo. Another spec written by the secretary in the marketing department.

In the service manuals they are both quoted as 20-20,000

I've had any number of them to bits and believe me, they are the same amplifier.

I believe the 9300 is actually based on the 2500 rather than the Ouverture and the Jarmans are inclined to agree with me!

Changed the typo on Beoworld anyway!! And Graham is quite right - the 9300 is 2500 based.