Personally, I don't have experience with either of these transponders, but my "transponder cert guy" recommends the Becker and won't "touch" a MicroAir.
It had to do with saturating due to Mode S interrogations and was the subject of a service bulletin (the one mentioned in my previous post in this thread) a while ago. They tell me mine has been fixed but I have not used it in a while - down loooong time for a rebuild.I was told the problem is with the software in the Microair. [...] Their software cannot handle it and freeze up. Thgis is what I have heard anyway.
I went with Becker. Ordered the 175W version simply because the 250W version was a backordered item from ACS.