I have the studio canvas and I like it. If your budget is 400 bucks, the sd50 is a much better buy than the ketron for several reasons which are probably mentioned in the review. If you can afford a little more perhaps the sonic cell is for you depending on what you are using it for. I don't know much about the sonic cell, never used it. I got the sd50 because I needed a replacement for Roland VSC when I upgraded to Win7. I tried the soft synths and still use them sometimes but I really liked the sound of vsc when playing midi files. I'm a sax player that uses biab for background playing in restaurants and private parties. I still use midi files for pop music. I know some guys don't think midi sounds good and prefer mp3's but I like the flexibility of midi files. I've also notice that I like the sound of everything better when I use the sd50 as an audio interface. I know sound is subjective, but for me I can definitely hear an improvement in the overall sound of biab and my midi files when played through the sd50. One nice feature is you only have to use a usb cable to connect to your computer. No midi cable, no power cable. The sd50 is powered by usb, batteries, or ac adapter. I also use it as my backup for my laptop. I've made biab mp3's so I can use the sd50 on short gigs without bringing my laptop. I just load the mp3's and midi files on a usb drive and off I go. Sorry for the long reply but thought I'd try to explain my reasons for owning the unit.

Dell Studio 16 Laptop i7 with 256 gig SSD
BIAB, Reaper, Encore, Sibelius
Roland SD-50