Thanks again for the input...great all around. I'm really picky about my images, which makes me slower to produce (not snail's pace, but not lightning, for sure). My images are good, varied...and often conceptual. They aren't incredible, and I don't see the return in spending a lot of money on them. I'm going for simple stuff, strong themes, people shots as much as possible, and technical expertise. So my acceptance rate on ShutterStock is really quite high. I'm thinking about 80% or better.
While they are on top of the noise thing, I try to work to IStock standards for noise, so that's usually not a problem.
Uploads have been fast an consistent. I have 300 images (growing by 4 or 5 a day now) and get about 10 to 15 buys on average a day. The more images, the more that creeps up.
I'm not funding my retirement account just yet, but do have a strategy for getting 2,000 images in my portfolio within about 12 months.
I know as the images get old they start to smell --

-- and that they'll fall off in terms of sales. So I'm working to keep fresh stuff coming.
I find ShutterStock to actually be more accepting than many of the others (IStock, Fotolia, DreamsTime). So I'm happy with ShutterStock.
By the way, I've started working as an Image Inspector for one of the sites (which will remain unnamed). What an education. It's real insight to the process to be on the other side of things.
I plan to share some of my experiences with the 26 sites that I have been supplying and just diving in to MS headfirst. I'll do that soon...
Cheers,
Scott/Creatista