Some friends and I just bought the 14 inch.
So far it's been working really well, we've made a lot of stickers. The only complaint about this is that the software (SCAL) doesn't always work perfectly and sometimes the sticker gets fucked up. Fortunately it comes with a pen that you can swap out for the blade and so it just draws the design. That way you don't end up wasting a lot of vinyl aligning it and stuff.
The cutter is pretty small and just sits on my desk. We live dorms, so there isn't too much extra space for stuff so this works pretty well.
A piece of advice would be to go in on the cutter with a few other kids. You don't lose anything by having multiple people co-own it if you're all living close by, and it makes it that much more affordable.