The Rectos were among the amps that benefited most from the new algorithms. If you want that Recto crunch but not so flubby and fizzy try the SOLO models. They're much brighter so I turn the treble down quite a bit.
I've noticed this. To start, I've never been a particularly huge Recto fan. I've always thought they're like... oatmeal. Oatmeal, like Mesa Rectos, always seems to be both mushy and sloppy, yet dry and flaky all at the same time. In this way, I've always thought Rectos are unsatisfying in both its bass and its treble ranges. A lot of high gain amps either have satisfying highs and clarity at the expense of girth or fatness, or sound big and fat in a satisfying way, but are lacking in high end clarity. The Recto somehow manages to miss both of these marks, for me anyway.
To this end, I've always thought the Axe's Rectos, even when more high end was EQ'd in to kind of artificially add sizzle, sounded a bit dull and lacked "impact" during things like palm mutes or even single notes picked particularly hard. Basically playing through Rectos have always kind of sounded to me like an exciting story being told by a sleepy, unenergectic person.
Not anymore though. There's more... well not so much *gain*, but crunch and what seems like more definition now, and the Master volume control allows fine tuning of this, and has suddenly gained a lot more usable range. They're still dark amps, but now they feel more reactive and alive. Maybe they've sounded like this for a while, but this firmware has caused me to focus a lot more on them for some reason, and I really like them.