With it's speed, durability, agility, range, very respectable weapons load-out, and comparatively low price, what are the Buccaneer's trade-offs/weaknesses?

The bulk of the Buccaneer's weapons are on its more exposed wings. If you're fighting a Buccaneer and can knock these out, you'll be able to seriously impact its potency, and ideally, push the pilot more towards running away from the fight as they'd be limited to just the weapons on the S4 mount. Beyond the weapon mounts, the more pronounced cockpit section is definitely going to create a more exposed cross-section to incoming fire.