This idea wouldn't work in Heroes, otherwise fans of the other factions would demand the same for their favorites – the ability to choose units. Nival won't go for it, and in the end, either the fans will tear Nival to shreds, or Heroes 5 will become just a simple trash game:cool:
And if people like having different races, you can simply change the skins while leaving the abilities of the creatures the same!
So, the angels will become red, but they won't "vampirize"!