I've tried the L1A and the M1A. I bought one of each.
The specs for the M1A are 14ish CFM, 28 dbA. That's the one I'm using currently.
The only thing I don't like about the Panaflos are their lack of an RPM sensor. I spliced on a 3-pin connector so I could hook it to the MB fan header, but it turns out that none of those Panaflos support RPM sensing.
Athlon XP Barton 2500+
Thermaltake Silent Boost
Windows XP Professional
Chieftec DH-01 Aluminum
Seasonic Super Tornado