I just got my C1 and have never actually heard or used NI's B4 (I hear it sounds great). But.....Mdorantes is dead right. Playing organ, especially jazz organ, is much more than just sound (consider that hardly any two B3's sound exactly alike). It has a lot to do with how fast you can transition from one registration to another, the key response speed, the volume follow throughout the range, the response to the expression pedal (very important), and the way it mimics all the little things that are unique to a real B3. But mostly, it depends on how you intend to use it.

If you are just going to lay down some (organ) background tracks, then a software sim would probably work just fine, but if you plan to gig with it as your primary (or only) keyboard, controllor keyboards and a laptop probably are not going to cut it. Although a little pricey (C1), you get what you pay for. You do miss the drawbars at first but you do get sort of used to it. Using presets works for me. I also got the Roland PK7a pedals but again this is a personal thing. I use them for slow tunes or when I need both hands for certain playing techniques.

It's no B3 but at 33lbs I'm kind of glad it's not.

chas

BTW, it sounds and plays better than the Nord Stage as it was designed from the ground up as an organ only. It also has a Vox and Farfisa setting but having never been a fan, I have no use for this feature.