Thanks for the answers!
Just to clarify, since scent has been mentioned, I'm referring to the unscented version. (Admittedly, some unscented detergents may leave a slight scent...) This is the cheapest option (oddly, the store has 2 box sizes, and the smallest is unscented, and the bigger is some scented formula).
The warmer the water, the better clothes get cleaner.
(Up to the point the enzymes denature, of course).
Heat killing enzyme action may not be a worry. IIRC, one issue with this detergent is that from what I could see in the ingredients there are no enzymes... Which is certainly a minus.