I think the reason why Surfer's post power up feats aren't "special" compared to his pre-power up feats is because Surfer's always been depicted as capable of doing practically anything via the power cosmic, so it just looks like more of the same, but it's actually not. Surfer has more power. His remorse holds him back from fully utilizing it to it's highest potential, but it's there.
Also, in Annihilation, the point where Surfer got his power-up was prior to the point where Surfer and Galactus were captured and placed in the Galactus Cannon. When Drax and Moondragon break Surfer out of his harness (after Drax had killed Thanos) Moondragon states that Thanos built in a failsafe to the device which was tuned to Thano's power level. Surfer's able to activate the power cell array, which was tuned to Thanos's energy signature, and Thanos was previously significantly more powerful than Surfer. A depleted Surfer, who couldn't stand up, was able to output Thanos's level of power:
http://i179.photobucket.com/albums/w313/illadelph12_prime/ann_05_006_zps2bd44faa.jpg
http://i179.photobucket.com/albums/w313/illadelph12_prime/ann_05_007_zps2fa568f4.jpg
http://i179.photobucket.com/albums/w313/illadelph12_prime/ann_05_008_zpsa49cde35.jpg
http://i179.photobucket.com/albums/w313/illadelph12_prime/ann_05_009_zps08822469.jpg
So either Surfer has always been as powerful as Thanos, or Galactus gave him more power.
I know it pains us all to admit this, but everything points to carver actually being right on this one. Every dog has it's day, it seems.