CafePress vs MySoti...suggestions?

I've been eyeing MySoti for a while now as a place to produce the newest Geoweasel shirts over CafePress, but I really don't know a lot about how good their products actually are. I'm interested in MySoti for a few reasons, namely because they offer a better and larger selection of colors for shirts and they cost a bit less than CafePress. But how is the quality? I've had trouble with CafePress' colored ("dark") shirts before, mainly in the area of how the color of the actual image appears on the shirt. Here's a shirt I made with them a while back and a comparison of the colors in the original drawing and what I got:


Most things were significantly darkened except for the gray, red, and white (go figure). Does anybody know if the color changes are this drastic with MySoti? I understand that when printed, especially on a dark garment, the colors are going to change, and I don't mind if they do a tad, but this was ridiculous, and CafePress gave no warning about that. And I'm certainly not about to go and keep testing different designs with different colors on different shirts until I figure out what's "safe."
The only other reasons I haven't done shirts with MySoti yet is because I'm used to CafePress, and also, MySoti only does shirts. I do plan to have other items, and I don't want to have each item being sold from a different site. That'd be ridiculous and confusing. Anyone have any suggestions?