Good discussion. And long list, too.
I've started crafting soundscapes quite recently, so I feel your pain.
I didn't want to be second Roach, I was searching to find my sound. Still searching...
Mainly looking into myself and "feeling" the sound I like, I feel
, I am missing in someone's music.
Listening to others' music was like searching for the sound matching your inner-sound.
I agree with others, I don't think you need all that equipment to create your own soundworld... Sure it can be an inspiration, but I'm sure you can get similar results with other gear not listed here. It's just a part of the chain, maybe even not the most important.
I think music is similar to cooking, the right ingredients and right amount of them can change the taste drastically.
And how you cook then later, so "reverb before or after mixing" question remains...
I'm certain mixing is the key to have great sounding track, especially in ambient music.
I don't think you need Oberheim to create your music. Other brand would offer you similar results, just in a different way.
I guess it's a "habit" for Steve Roach to use it. He likes the sound, timbre, and and it's great modulations capabilities which is one of the key factor to obtain complex and evolving sounds. I assume he's been using it for many years so you can hear it on many tracks, one way or another.
Maybe the sound stays well in the mix, cuts through well.
It's like custom flutes in Robert Rich's music. Or like Klaus Schulze using JD-800 in the concerts, since it's easy to change sounds quickly using sliders, etc.
Speaking of them, they bring another example of what Loren and Mike and other were talking. Look at Rich's "Trances/Drones". Prophet-5, bamboo flute, lap steel guitar, some bells and WHAT an effect...
And pioneering Schulze and his Irrlicht, Cyborg. He didn't even have full-blown synthesizer, just "mistreated" organ, VCS-3 synth (great for FXs), orchestra tapes and again, what an effect!
Or Tangerine Dream with early albums, like Zeit and Atem. Idea and execution. Or extensive improvising.
All those albums seem to be "simple" in tools, but so powerful in results...
You see, they didn't have all those fancy reverbs, and effects, but somehow the results are spectacular.
I guess once you have an idea for the great composition, you will find a way to record it.
Well, I don't want to sound like preaching, just some couple hundreds words of encouragement.
P.S. Maybe field recording is your way? It gives infinite source of unusual sounds, specially great for inharmonic samples.
You would have 1000 synths just outside your house. Or inside it, for that matter...