Dean J in MN
>I'll second John's assessment. If you want flat, a scrub isn't the way to go. A fore/jack is the tool of choice. If you want to get flat fast you want a fore with a good amount of camber to make it easy to take thick shavings. For me, a metal (or horned) scrub is too short to make a board of any appreciable size flat.
One of the sticky points of the BU jacks is the amount of extra camber you need compared to a BD. The geometry is working to lessen the curve on the blade when used BU. So, I'd suggest trying a good dose of camber on your BU jack. The length of your jack should be an asset in flattening.

-Dean