The only two Bose models compatible with the UFlyMike are the Quiet Comfort 2 and the newer Quiet Comfort 15. The QC3 that sits on your ears is not compatible according to UFlyMike because of different circuitry/connection.
I started flight training and when looking for a quality headset came across the UFlyMike. It turned out great since I already had a QC2 at home so I got a quality ANR setup when the UFlyMike was a little cheaper than it is today, IIRC.
I trained in 172's and have flown various other common, single-engine trainers. (Arrow, Warrior, Skipper, Cutlass, Champ and one Bonanza ride)
Compared to any passive DC headset, this setup is world's above. I tried my instructor's H10-13.4 and I bought an extra H20-10 on a whim for passengers. I did not like the bulk or clamping that I'm sure any pilot is aware of.
Compared to the Bose X and a Zulu, switching with my instructors, one in an Arrow and another in a new 172, the Bose setup sounded the same to me and my instructors felt the same.
Now, the Zulu has Bluetooth which is awesome for canceling IFR on the ground at non-towered airports and listening to music. With the UFlyMike, you can plug in an audio source but you have to handle the volume yourself as it will not cut out for ATC. I do not require music when flying (the engine noise is soothing) and if I do, I would rather have it plugged into the intercom and will utilize that feature when flying on long, VFR, solo xc's with no one to talk to.
Now there are a few cons as there is with any product.
1. You are limited to a left-side microphone since that is the side of the connection point on the Bose. Not a big deal to me and hasn't caused a problem
2. For those with smaller/shorter heads, the Bose may be too big. My friend's mother that flew with me didn't move the headband up at all but it also didn't slip. Your mileage may vary.
3. The Battery Issue - Personally, I do not think this is a problem at all. The headset gets really annoying when the battery runs low, cutting out audio and in general, just sounding terrible. If you are paranoid, you can change the battery when the light starts blinking as they claimed to do in the recent AOPA article but you will run through batteries have life left. I would never do this and just change it when it starts cutting out. Also, you can plug in any set of earbuds and place these in your ear for audio backup from the UFlyMike. The Bose are not technically necessary except to hold the mic.
But, I do change the battery when I know it's low if I'm going out IFR with low ceilings or in other possible high-workload situations so it's not something I have to worry about in a potentially stressful situation.
It's not hard to keep batteries relatively accessible in any airplane, IMO and the setup only requires one AAA battery that lasts for quite a long time.
From what I've heard, the Bose X is just about worthless when it's batteries die, at least in a single engine Cirrus or Cessna, as my current instructor told me. He would rather have his old pair of DCs in this situation. But, that opinion is not mine as I have not experienced it but have heard it from two other people as well.
I now have two of these setups - one with a QC15 and one with my older QC2 and I love them. I use the QC15 as it is newer and my old one's ear cups were a little deformed from age. I also have another QC2 ready for a UFlymike when I feel a need to have a third, nice headset.
If you are looking to purchase used, there is nothing wrong with the QC2 and very little difference with the updated model - Bose claims better noise canceling ability due to more advanced technology with its sound waves. I picked the older model up on eBay earlier this year for a little over $100 in great condition.
I never agreed with spending upwards of $600 on a aviation headset. Again, that's a frequent argument/caveat for us "Aviation=$$$"
I apologize for the length of this but I felt like I needed to present my experience and to help keep UFlyMike in business. They seem to be a great, American family business that has had some trouble regarding the Giant, Bose, and the FAA hurdles for TSO status.
EDIT: If you have any more questions, I would be happy to answer them. Disclaimer: I am only a user of these products and have no affiliation with Bose or UFlyMike other than as a customer.