I've recently decided to give my Daemons a break and play Space Marines (because I never have), but I get really bored painting the same colour power armour for an entire army. Therefore, the army never gets finished. So I decided to make my army a crusade, drawn from a bunch of different Chapters to hunt down one of my Daemon Princes. I intend to have units from the Blood Angels (just a few), Dark Angels (predominant), Imperial Fists and Salamanders using vanilla Space Marine rules. The army will be unified by a black left shoulder pad emblazoned with a scythe instead of the regular Chapter markings.
Do you think this is a good idea, and would you be OK fighting this force?