No problems whatsoever, but knowing the TYT 9800's reputation, I waited until they were on sale and bought an extended warranty.
If you noticed the mic has more buttons than the normal TYT DTMF mic you are correct. I did a lot of research before I bought the 9800 and the mic upgrade was one of the things I read about multiple places, so I went ahead and did it. The mic was very inexpensive and required a minor rewire, I think it was around $20. In freezing weather the chip in the mic won't engage the transmitter until it has warmed up. If I am anxious to talk right away I have to hold it on the heat outlet for a couple of minutes the first time I transmit. After that it stays warmed up.