My concept is that a 1 GHz, 4-5 Gs/s scope is about the fastest scope you can get that's really general-purpose. I used to have a TDS7704A that my employer paid $55k for (refurb!). Blazing fast--7 GHz, 40 or so Gs, but about 5 bits and ran Windows. It was in the rack right under the TDS684A, which got all the use because it was just so much nicer.
I could use something slower and newer, I expect, but constitutionally I'm of the they-don't-make 'em-like-they-used-to school--I have a 475A and a 466 analog storage scope, for instance.
Cheers
Phil Hobbs