I use SCAL (and I use the silhouette designer edition). I use scal mostly because my SDE became a hunk of junk and doesn't work half the time) but now that I have been using scal, I like it, its never given me a problem and it has layer panel like photoshop. I also think the tracing in scal is much better/easier too. I really like MTC but it doesn't work natively on a mac, without bootcamp or parallels, so I'll stick with scal.