Yes, the A and B models were later revisions of the un-suffixed models, and were usually better in some ways.
The 475A, for example, has a bandwidth of 250 MHz, but I have been told that it has "worse pulse response" as a result of the higher bandwidth. It also lacks a 2 mV range on the vertical channels, which is certainly a regression.
I'm currently restoring a 475A that I bought as a parts scope for my father's 475. It was quite evidently sick, and since the essence of my hobby is to diagnose and fix sick devices, I decided to try putting it back in working order rather than part it out. I fixed the bad +110V rail almost by accident, and am now working on the beam intensity amplifier (which had several diodes and transistors completely blown). Sadly, it looks like that might be all that is electronically wrong with the 475, and my fun will be over in a couple of week when the replacement transistors arrive.
I'm also fixing up my father's 2213, which has something marginal in the channel 1 vertical system, I have some residual marginality with his 475 involving cross talk in the vertical system and some stiff/scratchy pots, and I have a 2215A that I fixed the horizontal position adjustment on, but requires some adjustment to the 2 mV range on channel 1. So there's other fun to be had, but nothing quite as exciting as the repair required by the 475A.
Learning engineering minutia AND history and product lines.Engineering is just the minutia of history with extra math.
-- Jeff Dutky