There is no midsize board that will out grovel a grovel board on micro waves. But that assumes the surfer is capable of surfing up to the standard of making a grovel bord work. The whole point of grovel boards is to go fast and hit turns without the need to constantly "do the hop" to make the board work. If a surfer is, through lack of ability or experience, incapable of generating speed through turns (like pumping a skateboard) then yes, he is going to need a midsize+. If you are unable to generate speed through technique, the best you are going to do is trim and flow with an occasional turn on an oversize board that enables you to catch the wave easier and doesn't require as much surfer input to generate speed. I'm not putting you down, but a man has got to know his limitations.
Santa Barbara surfers seem to learn to grovel. Because they don't have any waves in the summer time. Most of the time they drive to Ventura which has mostly micro waves during the summer. Grovel or go golfing.
Bonzer Grovel (But GWS! You can't grovel on a Bonzer! I've read that on the erBB dozens of times!)