I took some of the Slim Fast LC shakes on my spring break trip with me and they didn't stall me. To me, they taste just as good as the Atkins shakes but they are less expensive.
And no, the shakes don't contain sugar alcohols, at least not the Atkins or Slim Fast ones. They have high fiber counts, which is good too.
I don't remember reading Aspartame in the ingredients. Course, that doesn't mean it wasn't there But they do have 2g of actual sugar per serving.