Heya Beyote
I can't speak for an S4R however I had an S4 and rode 750's and 900's and also Doon's old 800 hundie.
The S4 definatelty feels more planted to the frontm be fair to say the steering feels heavier with it but I like that feel.
The S4 undoubtedly will have more weight over the front and I believe this is good, Doons bike felt a little bit wobbly beside the S4 but again I beleive that would be weight related.
The S4 wheelied a lot easier (so am am told cos that is illegal

) because of the fat torque curve off the bottom, I would think the S4R would be even better at being illegal