Sounds like everyone is trying to find a cheap way to get back to what existed prior to the arranger era; a home organ with auto-accompaniment. I'm an organ player, or more specifically, a TONEWHEEL-type organ player. No 'B3' players that I know would ever accept two synths and pedals as a substitute for an organ; not even a consideration. Of course we're a biased little bunch so that configuration might work for non-organist who just want the convenience of two manuals (most people WON'T learn 'pedals' after age 60 ).

The configuration that works for me is my two-manual clonewheel on the bottom and a synth of your choice on top controlling an arranger module (or drum machine) on the side. In my case, I use the VP770 on top and the BK7m as a (very good) drum machine on the side. The VP770 has several good SN voices, is a fantastic vocal processor/harmonizer, and does a nice job playing the very good voices in the BK7m. This is my rehearsal rig and works very well when we rehearse (jam) without a drummer. The flat top of my organ (KeyB Duo Mk111) makes the synth of your choice very accessible with no controls blocked and a very short reach for the controller/synth's keybed. Works perfect for me. YMMV. It depends on how much your orientation is towards the organ.

chas