It has the same quality as the Key B Organ http://www.musicworldonline.co.uk/keyborgan//instruments/Numa/default.html

Before making a decision also have a look at these:

Hammonds own http://www.hammondorgan.co.uk/store/page1/page1.html or the Nord Electro 4 http://www.nordkeyboards.com/main.asp?tm=Products&clpm=Nord_Electro_4D

In addition if you have a computer or laptop you can buy the VB3 http://www.genuinesoundware.com/?a=showproduct&b=24 and control it from your existing keyboard. (Roland’s Midi implementation is normally quite reasonable)

BTW: I have heard the Key B Organ live, and for me personally I find it doesn’t quite have the bite that you get with a B, (its more smother like the A) but is a cracking instrument.

Hope this helps

Bill