This is a great idea that I've been practicing with not as much discipline as I would like. I've been slowly converging on an optimal (for me) paper size. I use the Pilot G-2 pen which writes well and feels good but is still cheap.

But I haven't been able to find a paper that is thick enough to allow for double sided writing. The composition pads tend to have really thin sheets that the ink shows through. Does anybody have suggestions?