I've dealt with both Ernie (SEVERAL orders) and T.U.S.
I can't say I've ever been disappointed with Ernie. The stencils are always spot on, and delivery was always quick. The only reason I've stopped using his services is that his prices have climbed up a bit since when I first started ordering, and the stencils never seemed to last too long, which admittedly may be my technique and equipment as much as anything.
T.U.S. seemed more reasonable on price, and the stencils did seem to last much longer. My only complaint with them, is that one of my marks that they printed seemed to come out somewhat "pixelated" despite sending them a non pixelated file. This led to a pretty sloppy looking mark. I asked them to fix it, and although it was better the second time, they still charged me a setup fee for what, in my opinion, shouldn't have cost me anything. I needed the stencils though, so I complied.
Ultimately, I decided it was just as economical to start making my own. Naturally there's a little bit of a learning curve, but I can make exactly what I want, when I want it, and not have to wait for it to be shipped.
Now, if was to go back to contracting them out, I'd probably stick with T.U.S., but only for text based stencils, as those seem to come out much more reliably with no definition/clarity problems.