I was thinking about making one two. Right now I am just using a cheap $50 dollar platform and it's getting the job done. But the thicker ones are alot smoother if you ask me.
I agree with Von Milash about just getting a small bag over a larger one because if you do it your going to learn it no matter what.
I think the title 5 by 8 speed bag is really good, I am currently using the everlast 6 by 4 inch bag and I love it. I call it my peanut bag because it's
so little.