The TBM is a very reliable machine, but gives good gliding performances and will maintain slow depressurization rate in case of engine failure. You anyway have quick access gazeous oxygen masks. Best glide speed is around 110 kts with a gliding ratio of 12 (if my memory is good). In comparison with the mustang it's more economical and offers more payload/range/speed (AKA productivity index) with same avionics (G1000).
Now if you're really concerned by the single engine issue the Avanti could be an excellent option as it's much faster and roomier than the mustang with competitive DOC.
In other words, the TBM and the Mustang are in one category, each with advantages and inconveniences. The Avanti would be competing with the CJs (speed and much bigger cabin, lower DOCs).
It would be interesting to know the average range and payloads you have to fly as it would to make a difference.