Well, I can't have any objection to *you* doing silks. If you want to make it useful and write it up - power to ya. I tried, and for me, it just didn't deliver in any of:
Setup costs
Speed
Quality of results
Complexity
(General electric found this out the hard way, FWIW, way back when - I sure did get paid to fix a lot of defective silked boards - back when I did that kind of thing)
I regularly label components just using copper...it's easy, but I'm not "in the make large amounts of consumer hardware" so I often simply don't bother - I'm making something I designed, after all, and by golly know where all the parts are.
Most silk paints will work fine as resists against most etchants. A little simple testing will show what works there - of course, you want a paint that you can easily dissolve off once done as well - the presensitized boards are either solder right through the resist, or a single wipe with acetone, literally just one stroke of a paper towel. It's the fuzzy edges and open tracks due to slightly missed coverage (especially when you get down to .004" - .008" tracks) that kill things with silks.
When you "get to volume" I'd personally recommend just using a PCB house (or perhaps even a job-house that also builds the boards and solders them) - that business runs on pretty darn low margins, it's very hard to beat them in either price or quality, much less both. Anything over a few $K - take it to Taiwan or even Canada. You save money AND it's better quality.
I do PCB's when I need 1 or a few. Maybe I want something special it's not worth it to have made, like the very simple board I demoed in that thread, where I wanted something a little better than perf board, only needed one, and wanted it simple and reliable.
I've also made a lot more complex PCBs, but once the design is good - get them made in a pro shop. They are such a small percent of the total costs it just doesn't make sense for me. It's cheaper and better to just buy an axe, rather than mine ore, refine it, forge it, make a handle...just to get an axe that will last longer than I'll live and only costs a fraction of my hourly rate to buy. I guess it's just different strokes.
After all, if the world economy collapses, as quite a few think it might - it could be a good business to be in for awhile, since the big houses will probably go out of business (but then, so will your silk process suppliers). But that's not something I sweat too much personally.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.