I love Ableton and I use the regular version.
A guy create music with installed Live Lite when he bought a MIDI controller. He likes it so much that even though he has paid for an upgrade to the regular version, he is still using the Lite version. He'll upgrade eventually though.
Live is awesome, it's a very different beast than Sonar but together they compliment each other very well. And with 64-bit rewire and all that, it's even easy