Here's my 2 cents..
you say you are not happy with the sounds you bought for your original Motif. At this point I think you need to step back and make a list of what type of organ sounds you want ( maybe a list of songs that have that sound) and what kind of control you want.
Then....go play some gear...motif ES or XS.
If Organ is really your thing and you are playing that most of the time when gigging...you are never really going to be happy if you are just playing a synth. You might want to buy a specialized instruemnt that unfortunately Yamaha does not make and if you do that....I would buy a leslie too.
If you have the money ( and muscle) to do this...youy might be happier on that path.
The obvious advantage to using the Motif ES or XS for organ is, well, no leslie...no, hmmm how would Alton Brown form the food Network put it...and no dedicated organ or "uni-tasker" keyboard.
There is still lots of tonal control on the Motif ES /XS regarding the organ sounds but even the sounds between those two are drastically different.
In the end use your best assets...your ears...listen and take not of what you like...then figure out the logistic ormoney, portability, gig rig compatability, and go from there. In the end it is "your music". The more time and effort you invest will end up paying off in the end as long as you stay true to your initial musical instincts.
Shoot me a private message if you need to talk.
I'd be happy to help.