Well…messing around with track lengths, LFOs, and odd sound modulations is one of the great joys of the Octatrack for me. Sometimes I sit down with a musical idea in my head that I want to hear coming out of the speakers, but quite a lot of the time I don’t have a clear idea of the end result, instead I conceive of some process involving feedback loops and modulation and I am curious to know what that sounds like. My impression is that you like the same sort of thing - emergent behavior of machines, discovering order in chaos and so on.
I’m not too sure how the AR would perform in this area. You get the rich analog sound with its own ‘organic’ quality that’s so hard to achieve with samples alone, but with one LFO per track (which it seems everyone wants to see increased), you don’t have the sort of complex modulation possiblities of some other devices, eg the inter-track modulation capabilities of the MachineDrum or the multiple LFOs and inter-track sampling and feedback capabilities of the OT. On the other hand, with 12 scenes and 12 performance controls available unt he pads, you have far greater options for performance modulation than you do on the Octatrack, where you can ‘only’ crossfade between two scenes at a time (although I haven’t found this to be terribly limiting).
The Plumbutter is something else, that’s a really unique machine and though I wasn’t kidding when I suggested the designer might be slightly insane, it’s also a device of great skill and craftsmanship. I would love to get one and mess around with it, but the probability that I’d purchase one right now is very low because it doesn’t look like a good machine for bread-and-butter drum sounds, eg when I feel like writing some conventional four-on-the-floor or breakbeats. In short, it seems like it only does weird stuff, and that you’d want to keep something more conventional around for your simpler needs. Of course, it might be that you either want to do experimental music to the exclusion of all else, or that you’re OK doing ‘ordinary’ drum sounds in the the computer and you want a device that you can get really nonlinear with - in which case, go for it.
BTW although it’s DSP-based software, have you ever considered tinkering with a Nord Modular? You can get a free copy of the demo software here which runs on your computer and has no time limits. A few of the more advanced modules are disabled and you can only have monophonic output, but it’s still a very capable and powerful tool - a lot of people who own the hardware keep a copy of the demo installed on laptops etc. so that they can patch when traveling or whatever without needing to cart the hardware along. There’s a large community with a massive amount of patches and resources at http://electro-music.com/forum/index.php?f=63. It’s useful and free and very intuitive, so you could patch and experiment on that while you’re thinking about which gear purchases to make. You could even have a go at emulating the Plumbutter by patching your own digital version - I use my G2 to imitate other gear all the time.