He gave three examples of what seemed to be character builds he'd like to try: Paladin, transmuter and invoker. I ruled out the Paladin due to their many restrictions in consideration to exploration, and replaced it with a warrior.

That said, bards are very good explorers. They have several utility options that no one else does. Still, they wouldn't be on my list of necessary components to a great exploration group. They can't heal like a healer can (e.g. plague, poison, healing sleep, etc.), and they can provide as much steady damage as a warrior or invoker, they cannot rescue like a warrior, they cannot provide immunity to all the elements, and the list goes on.

As it's been said before, bards are a jack-of-all-trades, and master's of none. The only one huge difference bard's have over anything else is mass sleep with zero drawbacks other than the lag of the song. Everything else can be done better by the other three (invoker, healer and warrior).