As written in the F5m kit thread, I recently rebuilt my PSU to lower the rail voltage. Mine are now running at 26V, but I may tweak them again to try a slightly higher setting. Bias current is presently set at 1.53A, but that is also under revision. The amp sounds really good at this operating point, and I am enjoying little tweaks here and there to see how the sound is affected. A point I made in the other thread is that I am not chasing more power delivery to my speakers, but trying different ways of biasing the output FETs to see where their sweet spot lies for the best sound.
The FQA and IXTQ parts that I am using are similar to what is being discussed for the ZD25 "Holy Grail" output stage. They are different from the usual parts found in the various Papa amps that we love to build. In particular, they are rated to dissipate a little more power, and exhibit higher transconductance at higher Vds. These attributes make it worthwhile to do some experimentation.
One of the more notable things I have found is that the F5m performs better with higher amounts of capacitance in the PSU. I built the new PSU with 18,000 uF caps and then added 24,000 uF onto the output terminals, where the boards and speaker returns are connected. This proved to be an essential addition, in that it improved imaging and instrumental details pretty much across the board. I recommend this for any builds where there is enough room, or even choosing a different internal layout to make the necessary room.