Our aircraft had a PMA8000B audio panel and it worked very well. Wanting Bluetooth functionality, and thanks to a member here who was liquidating some avionics, I purchased and installed a PDA360EX.
I was hesitant to make the switch to the EX because, well, the PMA8000 sets a pretty darned high standard and I was afraid of what PS Engineering might have cut out of the EX in order to get the cost down.
I should never have feared. PS Engineering will not cut corners on audio quality. The PDA360EX works beautifully. I'm glad I have the Bluetooth capability and appreciate how it is integrated, especially for telephone functionality. I've had several calls in the air trying to coordinate ground resources and most folks simply cannot believe one half of the conversation is coming from the airplane.
As far as having multiple comms, the transmitter inhibit as mentioned above is a great feature to use if you have a simple audio system. While that feature works, it's not nearly as nice as having a real audio panel. You might change radios over time, but if you've got a good audio panel and it's well installed, you will never regret having it and it will quickly become the one thing in your airplane you just won't change (unless it's for a newer, more feature rich model from PS Engineering, as I've recently learned!).
Never scrimp on the installation of the audio panel. Wire it right, especially when it comes to shielding of wires. After all, your ears are listening to that audio every second you fly. A well-installed audio panel is the core of an avionics installation so do it right and you'll be a very happy camper for many years to come.