In my Q700X I did two back to back 5 nautical mile loops, first using my Onno wing set at 208 cm. Then I repeated the loop using my 223.5 cm (88 inch) Novorca GP. Cadence with the wing and GP were 72 spm and 62 spm respectively. GPS indicated moving average speed was 4.2 kts with the wing and 3.9 kts with the GP. But there were tidal differences, plus I was slightly fatigued from the first effort, so the utility of the comparison is questionable.
The short length of the wing, and the short wing stroke compared to the deep long GP stroke account for the cadence difference. A rowing instructor once told me that if one wants the boat to move faster, then pull faster not harder, especially over a longer distance. I think higher cadence might be more efficient for me and am thinking of getting a shorter GP to get that cadence increase.
I greatly enjoy fooling around with different paddles, technique, and my GPS.