It's important to be precise about this. Rather than "preferred economy", I think you mean Main Cabin Extra. On this plane and route, the premium economy hard product (not only more legroom but more width, 2+4+2 versus 3+4+3) is sold as part of Main Cabin Extra. The soft product there will still be coach.

So, do you expect to be able to get this 2+4+2 MCE for free? If so, it reduces the incremental hard-product benefit of the paid upgrade. Many people consider the premium economy seat quite comfortable for a TCON (or even TATL) day flight.