Looks like an All-grain technique, I guess? I'm still doing mini-mashes for the foreseeable future. I don't consume/brew enough per year to justify the expense of all-grain equipment.
Right. You can make a fine bock without the "double decoction"! A good recipe, good fermentation temperature control with an adequate amount of yeast pitched, and a lengthy lagering period will give you a great bock.
Speaking of good recipes, do you know of one for Sam Adams Imperial Double Bock? I've looked high and low and the closest I've actually come on this board is a mail order kit that doesn't say waht's in it.