Lynzia
Who cares if the wood clarinet "plays better?" You NEVER take those outside... the extreme temperature changes can and very much will (or you know, already HAVE) ruin the clarinet. Plastic clarinets are JUST FINE if you have a great mouthpiece.
And besides, if you're doing a marching show, sounding "good" won't matter much if you play clarinet... no one hears the clarinets anyhow. >_<;
they only don't hear the clarinets if the show is written wrong, or numbers don't allow. With good instrumentation and keeping the woodwinds up front in close proximity to each other, hearing them is no problem.