Been to a Kiss concert where they were playing in their standard Eb tuning and then again a few years later when they went another step down to help Paul Stanley. Worst sounding performance I ever heard - and it wasn't the mix.Sludgy? It would not sound like Sleep or Electric Wizzard, worry not.
It would however help bruce nail those notes and it would sound way more balanced.
Megadeth abuses this but Iron Maiden could do it half step down and nobody would notice