I'll go between yours ...........
- They're two-sided. At least they look that way to me. I can't tell the front from the back.
Agree .... in most cases. Often times there is a difference where the pattern is not as predominant on one side or the other. If I am concerned, I mark what I am using as the backside with a safety pin, so I know without having to argue with myself later!
- They can bleed. I still throw all caution to the wind and don't prewash them. (Am I bad?)
Only you can answer that one! 
..... Lots of non-batiks can bleed too. Just as some batiks do not.
- They're generally thinner fabric than regular Q cottons.
- They don't stretch as much as other Q cottons.
They have a much tighter weave. As a result, fraying and stretching are minimized.
- I tend to create folds and puckers when I machine quilt them. Probably because they're thinner. They mistakenly fold and slip under the walking foot more easily....grrrr.
Perhaps conquer that with better sandwich prep with more stability from the spray or basting you do?
- They are more expensive than my "bargain basement" Q cottons that I usually buy.
Lately I have noticed that a lot of batiks are less $ than the new-stocked regular quilting cottons. There is such a variety of batiks, that many stores do not truly offer a good selection. Some LQS' in fact do not "like" batiks and just don't stock them.
- They can really brighten up a quilt in an instant! Yes indeed! .... but so can a lot of regular quilting cottons.
What else have you found out by working with batiks?
The more that I work with them or see them used by others, the more I appreciate them. I love the tonal variances that batiks can offer, whether TOTs or multi-coloureds. They can present some amazing chameleon backgrounds and constants.