I previously had a Roo23SS (08 model) and have looked at recent ones at the dealer that are the same, the slide is not a flush version. I agree the sofa was not the most comfortable, but if you look underneath you will see parts for the slide mechanism such as the place to manually crank it in and out. I don't think there would be an easy way to replace the current set up.
Pull-Rite 16K Super 5th
2014 Rockwood Signature Ultra-Lite 8289WS
2011 Chevy 2500HD - DuraMax (Just over 5000 miles now!)
Nights camped in 2014 - 21