I know it's been a while since you posted, but I just saw your question.
I have the slim line. The advantage is that you can keep it on as you turn the machine on and not ruin your machine. For me that works because I know I'm always rushing around and doing stupid things like that.

It takes me 3 minutes (if that) to switch back/forth.
If you are the more careful type I would look at what which system has window sizes you would use most and go with that.
Judy in NH