Thanks for the comments, everyone! I'm writing down your detergent requests for future rounds of tests.
zipdang-- Go for it! Sounds like you have quite an arsenal of detergents to use for cleaning tests.
Mike-- I didn't use bleach with the Persil for the stain removal test. I'd used bleach with it on my 'real' laundry in the past.
Shane-- Go to quixtar.com if you want to purchase SA8. However, the company has some political/ethical ideas you probably disagree with. But DAMN, they make a good detergent. I'm only going to use the SA8 on my white loads, and I bought a 150-load box, so it should last quite awhile. I don't plan to purchase any of their other products.
whirlcool-- I'm also interested in Arm & Hammer. I used the powdered version when I was just out of college and remembered liking it. Haven't used it in years, though. I'm especially interested if it's low-sudsing.
Chad-- Definitely save up for some Persil. It smells like no other detergent--very herbal (rosemary, specifically) rather than flowery/sweet as most detergents are. With shipping, my large box cost me about $67. The SA8 (with shipping) came to about $43.
Launderess-- Thanks for the word on Tide with Bleach Alternative. As always, your knowledge and Anglocentric vocab are always appreciated.
Scott-- I'm also interested to see how Tide w/ Bleach Alternative stacks up against the other 3 Tide products I tested.
I want to test the Sam's Club Generic faux-Industrial stuff, too. It seems to do a pretty good job. And it's dirt cheap.