As I remember the DB-610 engines were really just 2 DB-605s mated together, and they had huge problems with them. They finally solved enough of the problems to go into production, but the He-177s really spent most of their time sitting on the tarmac until it was too late for them to make a difference.
I'd much rather see one of the JU88S versions, or maybe even one of the anti-tank P variants.