if you want the stock messaging app, stock launcher, stock dialer, stock e-mail app, stock camera, DLNA, HDMI output, stock gallery, you should stick with a blurred ROM.
you really have to check them out for yourself. i would try out liberty 1.5 since that seems to be the blurless ROM of choice around here (even tho i had issues with it) and Apex 1.4.1 (which i am running now) and see if you like one better than the other.
blurless does seem to be a little faster, but Blur ROMs have always gotten much better battery life for me and they always work better for me.
Blur is Motorolas skin, or overlay, for Android. Just like HTC has Sense, and Samsung has TouchWiz.
You can't turn it off really. But you can use a different launcher(aka home replacement) and that disables Blur more or less.