I agree with that size of a lake being 'marginal'. -But it's better than not sailing at all.

It does get boring sailing back and forth across a small circle, if you are by yourself. But with friends and some beer, it is quite entertaining! Also, a slow wind will make a small lake seem HUGE. If the wind completely dies, and you forgot your paddle, hand-paddling will make the lake into an endless ocean! If you flip you boat, you won't need Gary's Solo-Right.-You just float to shore and walk the mast back up.

Seriously, get the Hobie. It will be fun enough. The wind is never the same, so there is always different experience each time you sail. The wind is steady, or puffy, or punchy, or light, or moderate, or heavy, or rising, or shifting, or...