run free and interact in unpredictable ways over time
Starting to sound like we are doing very similar things. I deliberately record my loops live and at arbitrary lengths so when mixed at performance time they combine in a semi-stochastic way. That way the music is often as new to me as it is to the people who might be listening. Fun fun fun …
Yes, this! 
And definitely sounds like we have a similar approach - I love the unpredictability of a process like this! I used to gig with stuff like 4 boom boxes with different tapes and a nightmare of interconnected pedal loopers, but this is much more fun and musical. Closer to my process at the computer, but feels more like playing an instrument - like having 8 different extremely long tape loops you can individually manipulate. Tons of fun!
Actually in the midst of preparing my first live set with the A4 hooked up to the OT. Works like a charm even for a newbie like me - you can just set the A4 to recieve clock + transport and nothing else. (Also, judging from the various Elektron wizards in here, you can do all sorts of wilder things like live sampling the A4 in the OT and stuff…one day I hope to get into this too!) 
Just FYI there are several methods to make quantized 8 bar loops… I make 16 and even 32 sometimes… Lots of threads/posts out there with details… Once correct recorder settings are made its only one more button press or combo press than a 4 bar loop… It’s not that hard, or I figure it can’t be easier going to use another piece of gear than pressing one more button…
you can do all sorts of wilder things like live sampling the A4 in the OT
Um. Do you mean something like:
Can the OT replace my looper? I’ve got a Boss RC505 that is nice enough but isn’t spot-on perfect . If I can sell the RC505 that would get me closer to the OT … but only if the OT can replace it …
I have an OT and I can agree, but not at -all cost- with this.
The most important thing, and you state it when you say " I find attractive" , is that the audience (99,50%) does not care if there is a computer on stage or not.
Do it for yourself. Because you want to use an OT or xx piece of hardware.
The other 0,50% are the YT trolls on ATC by the way…
You can easily record an A4 loop on the fly. Then you can use the fader to mix between the sampled loop and a new live pattern on A4. You can record more loops and mix between them all if you want. You can even make rearranged sliced patterns using the recorder buffer placeholders, and when you sample the A4 it can be played back sliced/rearranged/warped in real time. Up to 8 different A4 loops or sliced/warped remixes can be played per pattern… Plus lots more stuff can be done!
I sold my RC505. It was working really well with OT but I wanted to focus on OT only.
Rc505 is much more straightforward than OT, better for seemless loops because of a better crossfade (fade in / out) implementation, very long recordings possible, but much more crazy possibilities with OT. It can be used as a regular looper, but you have to configure it for that, to your taste.
I bought a RC202 though, but I don’t use it. I
I think all Octatrack usage is potentially weird… 
I would love a link to a thread about how to record 8-bar loops
But just real quick, how would I record exactly 128 steps when the maximum step length in the record setup is 64 steps?
Turn on dynamic recorders in mem config… (There’s a bug where you have to either power cycle or save and reload the project after this…)
Set rlen to max… Set mode to one2… (One2mode allows you to define the sample ending)
Set qrec and qpl to 64…
Probably save part and project so you don’t have to ever redo the men config or recorder setup.
Press play…
During a cycle press track+rec… (For manual recording) the recording begins on the next cycle.
On the last cycle of your recoding press track+record again. For 128 steps you just press the combo during the second cycle…
Less button presses with pickups, one shot recorders, or enabling quick record mode, other variations exist…
It’s good to customize mem config too while your in there, set the number or reserve recordings you might need and they’re reserved time, as to not reserve too much and take away flex memory…
better crossfade (fade in / out) implementation,
Ack. Given that i’m not totally wild about the RC505’s crossfade, that is good to know. Still think I want an OT though. Saving pennies.