Getting back to Overmars' original question, a sprial dive is an unstalled condition of flight, and so technically should be recoverable in any aircraft. I fly the baron full time, and have not seen any reference to a reluctance to recover from a spiral dive in the handbook, or any other texts that I have read.
I do know that there is a reference to the unknown spinning characteristics of the aircraft due to the fact that it was never spin tested. With reference to John_Tullamarine's comment about the aircraft spinning inverted, if positive 'g' is held during the stall recovery (in other words, if the c/c is not pushed forward excessively during the recovery), no aircraft will spin inverted.
The spin characteristics of the baron, although untested, would be fairly flat due to the Pro-spin characteristics of the aircraft, also found in most light twins. Flat spins, by their nature, are harder to recover from than a conventional spin. Flat spins can be entered through a miss-use of aileron, and / or power during a conventional spin, or the mass distribution through-out the aircraft. My recommendation. DON'T TRY IT, especially in a baron.