Oh, I forgot to mention the other reason I tend to use my Ipad for convenience....fast start up.
even when my tablet is asleep, I'm going to wait at least 20 seconds for it to be up and usable, while my ipad is up in about 2 seconds.
Now, having said that, in classes I use my tablet far more frequently than my Ipad.
So to sum it up...I use the ipad when I want carrying ease, long battery life, and fast access. I use the tablet when I'm going to sit somewhere, put in a lot of info/long period of time, or really need to use multiple windows.
I've never used the slates...I've wanted to, and their handwriting recognition is likely better (the slates have been around for quite a while) but I'd be worried the windows based software would still have a slow wake up time.
Enjoy the adventure; live life creating great stories to share with the grandchildren.