Yes, it downfloods before it turtles
I've put a Hunter 23's rail under water on several occassions, and once, even had water coming into the cockpit. No capsize. Downflooding is more a concern with small boats like the 23 than with larger boats like the 31, for several reasons. (a) Smaller boats are tippier. You can downflood a Hunter 23 in a good breeze. Waves aren't required. (b) Smaller boats have lower downflood angles. Bigger boats have more beam, but companionways stay the same size. (c) Smaller boats sink more quickly. If a 31 gets knocked down and starts to downflood, it likely will right itself before it takes on enough water to sink. The 23 takes water on at the same rate, maybe faster, but it has FAR less buoyancy.These considerations apply to most boats of the same size and type as the Hunter 23, eg, the Catalina 22, the Pearson 23, etc.