Title says it all really.
Is the A4 and OT similar in workflow, and the way you use menus? (minimal to no diving)
A4 UI is infinitely simpler and much more intuitive, lots of things will feel clunky on OT by comparison, don’t assume limitations you may be resigned to with OT apply to A series, e.g. multi trig actions
the A4 is easiest to master of all by common opinion, for me the OT is still a fascinating temptress, insanely flexible, the A4 scores highest on nuance in sound, it’s very deep and capable of a broad range of sound
I dunno, will you?
only you will know 
I had an OT before I had an A4 and the UI wasn’t exactly the same…the workflow is kind of similar though (I prefer the OT).
I like both and wouldn’t get rid of either…you can expect the same sort of menu diving, shortcuts, sequencer action, and some nice sound synthesis.
If I had one complaint about the A4 it would be that the screen is so tiny with lots of menu diving…however, that complaint holds true across all my elektron gear. The instruments are good enough that I overlook that drawback on all of them.
A4’s pretty straight forward. OT is a bit more complicated. Some people excel when things are messy others fail when things are too easy.
I picked up an A4 and only resorted to the manual a year or so later. When I got my OT this week, I scratched my head for 20 minutes trying to figure out why there is no sound coming out…so I ran to the print shop and printed that 189 page manual. I think if you love OT you already love the A4.
I went MDUW>MNM>OT. If you already love the OT, anything else is cake. It probably took me 24 hours to grok the OT, and after 12 hours it felt like Elektron had made a machine just for me. The A4 is my next conquest, and I don’t think I’ll even need to read the manual at this point.
Ok, so the amount of menu diving is the same?
Looking at pictures it seem like every section has its own button for direct access to parameters… Any paging there?
I really don’t menu dive that much. Once you have your track sounds set up you can begin jamming and not have to dive at all. If you do your diving beforehand, you can also set up performance macros which takes even more menu diving out of the equation.
I don’t own an OT; but the A4 is incredibly intuitive. This forum helped a ton getting me going with Elektron gear. If you know anything about subtractive synths then you’ll find the A4 a breeze.
Also, the A4 is incredibly versatile. I’m doing soundtrack type drones on it; and you’ll find tons of EDM videos online. So, that shows how you can take this synth in two very different directions.
Edit:
One thing I like to do is clear the track sounds completely and begin with raw oscillators. Then I build my own sounds from there. A very quick double-click and you can jump into the soundpool to grab a drum sound or something fast.
A4 has some significant menu diving. The performance page comes to mind when compared to setting up scenes in the OT.
Also, if you want to set up some type of modulation source and destination for velocity, there’s some diving.
Moreover, to set up the Poly mode, you gotta dive.
In some respects there’s slightly more diving on the A4 than the OT.
At least with the OT, you can set up a template project and just reload the template, or save it as a new one to avoid a lot of the initial set up/diving.
With you 100% re the tiny screen size. And its resolution is so low that it’s difficult to distinguish some characters. Hopefully Overbridge and the external editor will overcome that issue.
There is no synth parameter that takes more than two button presses to get to.
Menu diving? More like menu wading…
sure there is…dig a little deeper
but like I said, I don’t mind moving around to get to things and adjust them…it’s a deep synth…however, using that tiny little screen to do it isn’t fun at all
that compared to… say… my sub37, which is also a very deep synth with a little screen…completely different experience
MOOG just solved my complaint about selecting some of the “millions of modulation destinations” via their little screen…so I can’t complain about that anymore
edit, your term of “menu wading” is a lot better
No joke, but I love the tiny screen. It reminds me of my old Game Boy that I hold dear in my memory.
One night we were chilling with a bunch friends at and my buddy was playing the Game Boy and I was like “man this Zelda game is awesome” and he says: It’s Tetris…
truth is…I’m getting old so I like big displays and or direct access (a la sub37)…though I’ve seen lots of people complain about the small screen on the elektron units (even young people)
back in my gameboy days it didn’t bother me
Subq- I’m talking about the actual synth parameters- oscillators, envelopes, etc. I realize that there are some areas of the whole instrument that are slightly less accessible.
I was prepared to be frustrated by the tiny screen, and I certainly don’t have sharp eyesight, but it has turned out to be a non issue as far as I’m concerned.
A stupid design decision though, to be sure…
You can set up the deeper ones as performance prefs too.
The screen actually doesn’t bother me. I sit in front of two giant apple monitors all day at work. my eyes thank me that i’m not searing my retinas at night anymore. 
I’m the opposite, after looking at high PPI displays all day everything else just makes me mad.
Recently got glasses for work in front of the screen, big difference! But never felt I had any problems with the display on Octatrack even before glasses. Is it worse on A4? It seems like its smaller, but less info, same GUI size?
No, the GUI on the A4 is smaller but not too tiny to make out what you need. Yes, you WILL love the A4 if you love the OT!