I have a 485 and a 7104. The fragile CRT of the latter discourages regular use unless needed. Reed refurbished my 485 and obviously it's a really fine instrument.
I'm mulling over getting a 7904 for more routine work because I find the overshoot on DSOs very annoying. My 1.5 GHz LeCroy has a spec of 17% overshoot. I don't consider anything above 2-3% acceptable. I've asked Tek for a step response for a 3 or 4 series 1 GHz DSO using one of Leo's pulsers or similar. After my adventures with Keysight's MSOX3104T and the Rohde & Schwarz RTM3104 I don't want to get a demo unit unless it has an acceptable step response. It will be interesting to see if I get one.
I've never touched a 7904 and have no knowledge of them other than what I've read on TekWiki.
So some questions:
which is the best choice from a long term support basis, 7904 or 7904A?
what plugins? 2x 7A19 and 7B92 + ???
common issues (e.g things like the 576 transformer problem)?