Hello BlkNotes
Your quite correct I play the Abacus running OAS 6 software. (And looking forward to the release of OAS 7 software, £150 for a virtually new instrument)
I have compared most of the keyboards you mentioned, as in the UK we have Organ and Keyboard festivals, were most manufactures are represented, as these are mostly week long events, it means you have plenty time to try all the different keyboards and Organs, with no pressure to buy, but if you do decide to buy most manufactures give special deals to those attending the festivals.
The styles in OAS 6 can contain up to 2 drum kit tracks and 5 to 7 (Depending on model) sound tracks, the styles consist of 4 variations, 2 fill ins, 2 intro/endings, with real time sliders for volume control of the various tracks, (Midi files can also be assigned to real Time sliders) Akai samples and VST instruments (With the use of the inbuilt Cubasis software) can also be used in the styles. (OAS 7 will include an integrated VST Host and Giga sampler, so I think? the styles will be able to use these Giga sounds as well)
One of the best features are the Hybrid styles called Real Drums, which integrates a Wav file recording of a Real Drummer playing a Real Drum Kit into the style sequence.
The styles themselves are I think done in house, rather then by a dedicated style producing company, and so some of them don’t sound as sophisticated as other keyboards.
The Best styles I have heard on any keyboard (To my ears) are the styles on the Roland G70, Tyros styles I find over complicated and very song specific, and so to me are not very impressive, the other instruments you mention are, in there own ways similar to Wersi styles.
Hope this helps.

Bill