I suspect a large part of the is the new default for the "Speaker Thump" parameter. I've been backing that value down from the old default value of "2.5" on my existing FM9 presets as of late and indeed the low end becomes less cloudy and more focused, as well as not blanketing the mids/highs as much either. I didn't have a problem with it at "2.5" but I'm finding backing it off to ~1.8-ish is better.
Backing down the "Speaker Drive" from the old default of "2.00" to "1.00" also goes a long way to clarify the mids/highs too. I'm setting this to ~1.4 after rehearsing with "Speaker Drive/Thump" with the new default values. I'm anticipating tweaking those further after I get v6.xx installed since there are new modeling improvements and interactions.
Add to all of that:
-Improved Amp block triode algorithm
-Improved speaker compression and amp interaction modeling
...and we have a new recipe for tonal, and feel, goodness....ya man.