I've been using my trusty MFLB since July of 2010 with no issues whatsoever. The only 'problem' I had with it were the rechargeable batteries. The MFLB crew finally released a PA beta and I ordered as soon as I heard about it.
First off, kudos to the team for shipping the PA so quickly. I received mine in less than a week!
As for the PA itself, it's exactly what I imagined it would be. It feels like I'm hitting a fresh battery every time. When I try using the PA with full power though I hear a very low sounding buzz. Is that normal? I use the PA with slightly less than full power, just in case.
The build quality is nearly impeccable. I have one slight concern with it though. The base of the black cable that connects the battery with the base seems loose. I've highlighted the area I'm talking about with this picture:
http://imgur.com/1px13.jpg
I hope this looseness doesn't cause the PA to stop working after a few weeks of use.
All in all I'm very satisfied with the PA. Thanks MFLB team for once again, improving my quality of life!