Thanks for all the comments everyone. Your participation in this "market research" has been most appreciated!
Here are some thoughts of mine...
35mm is probably not possible, but 120 should be. 4x5" would definitely be the bread and butter of any screen-plate product line, though you'd have to make 8x10" available just for the sheer sake of seeing something like that!
I agree that it's gotta be on film, no plates. ISO 25 seems like a good benchmark, but I suspect that means you'd have to have an emulsion of 400 or so. The screen will absorb a significant amount of light. I think good reciprocity characteristics (or at the least, well published correction tables) would be ideal.
Processing could be normal negative development, yielding a color negative to be printed on RA-4. But let's face it, more realistically they're going to be scanned and shared online. Scannability is crucial to the success of a modern screen-plate, and my experiments with slide-film reseaus show that the denisty is quite a bit more than my Epson 4990 can handle. Something to think about...
Negative processing would allow for pushing, which might be interesting. Reversal (positive) processing would be more rigid.
I think it'd be cool to team up with dr5 for reversal processing services, while also having a well tested procedure for obtaining good results at home. This would be the "recommended" method.
The results aren't going to approach anything resembling E6 or C-41, but that's not the point at all.