Don't like this method for several reasons (as I'm sure you guys don't either). First....too many points for your line to break. Having to tie 3-4 line connections makes for several points of weakness and possible breaking. Secondly.....WHAT A PAIN! Having to spend all that time whipping out different lines and tying...no thanks. Lastly....just looks bad. Bunch of knots all the way down to your fly...na. So pointless when you can just buy a beautifully tapered leader for some change.
A 12' leader! Holy Crap! My leaders go around 5'-6' at the most, then I'll add 2'-3' tippet to that. I couldn't imagine nymphing with that much leader! I'll stick to my straight fluoro for nymphing, and tapered fluoro for drying.
-Rich