GK "claims" all the growl we came to know, and love is still there.
It ain't! I checked.
The new line of GK amps sent me running into the arms of Mesa Boogie. And I was a loyal GK user since 1978.
I owned every amp they now produce that was 800 watts and up. Could not get a usable sound. Through quality cabs to boot.
I would advise steering clear of GK unless you know what you're getting into. Perhaps their sound is what you want. I was left disappointed.
I don't like to dis on a company. Especially one I have decades of history with. But GK is done.
So what you're saying the new ones are not even close to the old RBs? I've never played on the original, I do have the MB200 which is the most basic version of all, and can't truly compare it myself to the RB, but it does have some growl to be honest. I'm saying "some" cause there's no trim pot on this, not even volume pot, the gain pot is the volume and the sound changes as the volume goes up but I think the general GK characteristics are there. It's clean, punchy, articulate and fast and I love it cause of that. Especially for its size.
I just want to upgrade to Legacy or Fusion S. Someone in here has the older MB Fusion 500 and the new Legacy 800. He compared them side by side. Apparently the Legacy is pretty close, probably very very close to the RB and can recreate that growl, but the Fusion is a little more mellow. Also, apparently the bass, the low end on the Legacy is tighter and more defined, rather than rounder as on the Fusion.
By what the guy said the difference isn't drastic but definitely present, while both exhibiting GK characteristics and the Legacy being still very GK.
The overall sound will depend on the instrument too. I have a custom bass I made myself during covid with an LP and custom preamp and sounds crazy good on GK, even on the tiny MB200.
This tells me I should lean towards the Legacy for the upgrade, and now you came in with this

. But I wanted some more feedback.
The visual design on the Fusion S is awesome btw. I wish Legacy looked like that and was pushbutton on the knobs rather than separate switches.