Hi to all,
Don't know about the Sennheiser's being garbage. I wore the HMEC-25's for two years on the 737 and liked the way they performed. Got to compare them side by side with FO's that had the UFlyMike setup. Comfort wise, the UFM is more comfortable because it sets over your ears, versus on top of them like the Sennheiser's. When the noise cancelling circuitry is turned on the Sennheiser's were actually a little quieter, but not by much.
One thing to watch for is that the UFM headset is TSO'd, but the headset they mount on is not. They are marketing it on the premise that the headset is only an accessory that the actual headset is mounted to so that does not need to be TSO'd. The issue is that if the batteries go dead, you lose all capability to hear anything. What you do is wear the earpiece supplied by UFM as a backup and then they are fine.
They have a little smaller footprint than the Sennheiser's do and you can use them in back as well. You may have some issues with the UFM piece sliding out of the headset, as my neighbor uses them and has a rubber band to hold them in securely, but otherwise no issues. Some companies have an official position against using the UFM setup, so your mileage may vary.
Not a bad setup, but to say the Sennheiser's are garbage is a little harsh, just my experience.