I’m sure it’s great - I have one in combo form.

But the 500 head is no longer generally available, after all.
If the 200 hadn’t been discontinued, I might have bought one when I was on the lookout for a head to go with my spare 210 at our rehearsal space. As it was I had to go with the TC Electronic BAM 200, since a Rumble 800 HD would clearly have been overkill, both in power and price. I’m happy enough with the TC, it sounds good and works well. But I’d have preferred a Rumble if I could get it, hence my hankering after a Rumble head in the 300-ish wattage range. With the 210 cab, it would also have been a good backup gigging rig (not that there are any gigs on the horizon at the moment).