"My understanding is the boom is in the way on such small boats. I'm buying a Hunter 25.5 and was told if you have one made where you can stand up, you can't sail with it up. If you want one where you can stand up, you can only use it under motor on in the slip. Is this true as far as you all understand it too?...Also, what can one expect to pay for a 25.5 bimini?"?
On a 23.5, if you stand while coming about, you will get "boomed". I've never measured it, but I'm guessing that the boom is about 5 1/2' above the cockpit sole. So, no, you cannot get a bimini under the boom and expect to be able to stand under it. That's the case with most small boats.