I found the transition from the MD80 to the 737 200 much more difficult than years before going from the 737 200 to the MD80 in the right seat. Learning automation and still having your manual skills intact is easier than losing your hands on flying skills because of auto everything and having to do everything yourself again.
I ended my career in the B757 flying manual approaches rather than going to the B777 so I could enjoy the last few years. No stress, no surprises.