Here was my thinking on the 800.
I like the Fender stuff and I wanted a separate head and cabinet for reasons of versatility and portability. You can take it apart and each piece would be easier to carry and you only have to bring what you need for any particular situation. Also, as your tastes change you can swap in different cabinets or heads without having to spend so much money replacing everything with different combo amps. That was the theory.
As to how powerful it is, @Gio described his 600 watt rig like this…
I get their is a huge difference between Fender and Mesa Boogie. I’m just using this to illustrate the power of even 600 watts.
I just wanted something that could easily work in a full band situation with enough wattage that I didn’t have to worry about it for a long time. What I wanted was the Rumble 800 head as a 500 watt amplifier. I looked at getting a used Rumble 500 head (they’re discontinued) but there is a known problem with the volume knob that Fender won’t fix and I didn’t want to deal with that. So that left me with the 800 as the only real option if I wanted to stay with getting a Fender head.
Originally what I wanted was a Rumble 500 but with a 15" speaker. The closest thing Fender has is the Rumble 200 but it’s too expensive for what it is and for the money it just doesn’t seem like a very good deal compared to buying a Rumble 500. But, if I wanted 15" speakers then I had to go separate head and cabinet.
I know all that is all over the place. Just consider it an example of the frustration that can happen when you think you know what you want but it isn’t made that way.
Then this post happened… How can I be heard through the mix ( a non scientific approach to sound) - #53 by Gorch
That’s when I decided, no matter how much I really like the Rumble 800 head, I had made it all way more complicated than it needs to be.
I returned the 800 today and ordered a Rumble 500 combo. If I need more, I’ll just pick up a second 2x10" cabinet.
With that in place I’m going back to focusing on my playing. In a couple of years I’ll revisit what else I might want in an amp.