Not necessarily a fully fledged 'op up', but:
Flew DJ 1142 yesterday on VH-VBU. Advertised and flight was sold with only Saver/Flexi options (no premium/J).
I had checked in using the new 'mobile phone' system (seat 8C - Silver so row 8 is as far forward as I get to preselect), and handed over my phone at the gate. The attendant didn't scan it, instead asked my surname and said she would print my BP. She punched in some query on the gate computer, and printed out a boarding pass with 2D. I didn't say anything as I figured anything further forward was a bonus, and was hoping it might be one of the premium layouts.
Low and behold this bird had been refitted with the new interior (old exterior), with 8 comfy J seats up the front. The two pax in front of me were remarking that they were DJ Gold and they thought that must have been why they were bumped to the front. 1D/F and 2A/D were occupied, the other 4 seats were empty.
No J service, which was fine, and why I guess it's not a real 'op-up', but it was close to the best thing that's happened to me flying economy everywhere...
Fare type was F (cheapest of the cheap sale fares) and I am nothing but smiles after that experience.
The only problem now is getting back on a plane knowing it's not gonna happen again haha!
YMMV, HTH.