Yep, Preston's got it pretty much on the nose. If I was going to add anything I'd also note that in the context of a game the Emperor has to be protected from enemy attacks by other friendly ships, the Retribution can look after itself amply as long as someone is covering its tail, so it can give long range support or even join the Lunars and breach the enemy gun line, the Emperor is naturally constrained to only long range support. The Retribution also gives the Imperial fleet a big dose of something it is very short on, 60cm lances combined with a big 60cm battery. When an Imperial fleet fights from beneath the 'long arm' of a Retribution and some nova cannons (ie a Mars class) it makes it very dangerous indeed (and yes I do like the Retribution better).