Always beating a dead horse on decoction or not, but FWIW. I don’t decoct, but I find I lose a little bit of the malt character and color if I don’t so I always adjust with a longer boil (at least 90 minutes and up to 120 for a regular Dopplebock) and sometimes will add in a little extra Munich to compensate. I also use the Hockwurz step mash regime mentioned in Gordon Strong’s book and have had a lot of success getting nice clean finishing German lagers.
