When you say you're working on your ATP certificate, does that mean you're preparing for your practical test in the mooney and Cessna, or that you plan on going to work in mooney's and Cessna's once you've obtained your ATP?
In a professional cockpit, you can get by in most cases with a fairly light weight, simple headset. Today on our flight deck, we had one wearing a plantronics starset, and two of us wearing simple telex airman type headsets. Very light weight, no noise cancelling required.
In a light airplane, nearly any headset will work. The Bose X is very comfortable, as are the lightspeed headsets. Any basic david clarke type headset with an upgrade using the oregon aero earseals, hush kit, and headband is reasonably comfortable, with the ANR not really needed. It's nice enough, but if you're on a budget, it's not necessary.
You needn't pay full price for a Bose, or any other headset, either. I got quite a bit of use out of a Bose X purchased on Ebay.
What headset is appropriate for you really depends on what you'll be flying. You should also ensure that your headset will not only be compatible with the avionics in use (primarily a microphone issue), but with any intercom that may also be used. Even in a simple intercom system in a light airplane, mixing headsets can create impedence problems that prevent communication. A good example might be your own portable intercom being used for flight instruction; having different headsets between you and your student could create a problem. Getting into an airplane that doesn't permit you to use your headset will make the headset relatively worthless to you...determine exactly where it will be used, try to borrow one and try it out (for several hours; be sure it works, and it's comfortable), then decide.