Bob, the sounds you like to play suit the VR760, right out of the box[no need for SRX boards]..
As for Pros and cons..the XP80 and VR are different concepts..the XP80 is a workstation and the VR is not..
The XP is a great controller[probably the best available]..Detail editing of sounds. A powerful sequencer..
The VR is none of the above..
What the VR brings to the table is eactly what you preferred in you initial comments..
Unsurpassed Rhodes samples and patches[not DX ish].
Organs and parameters that the XP can't compete with..
Quick changes , splits and layers of the 3 groups[piano/organ/synth].
It sounds like the rhythm section on the VR will even meet your needs..
The VR key feel is better than the XP80[XP is not that bad]..

Learning curve and getting around is much harder on the XP80..
Realtime performing is more enjoyable playing the VR...

If you can live without a sequencer,don't need to control more than 4 channels, and are not into overkill sound editing,,and can realy get into drawbars and other realtime control.......Go for the VR760