Here are the unit numbers i usually use, with reasons:
Vanilla CSM: 10
They're comparatively cheap, so fill the unit up to 10 and throw them in a rhino.
Plague Marines: 7
Magic number of Nurgle, and also they're freaking expensive. More is acceptable, but i don't find that the extra bolters benefit me all that much.
Khorne Berserkers: 8
Again, magic number and cost consideration. Plus, anything over 8 tends to overkill like crazy, leaving you vulnerable during the shooting phase.
Noise Marines: 6ish
No personal experience here, but i get the impression that keeping them small and loading them up to the eyeballs with Sonic Blasters is the way to go.
Load them up with 5x meltas and go on a suicide run, usually with Outflank/Rhino.
Usually don't use this unit, because they're terrible from a competitive/efficiency standpoint. Fun in friendly games or for fluff reasons though.
Anyway, unit of 5 for running about stabbing things alone or to join Kharn in his Land Raider to stab things. WAAAAY too expensive for what they bring to the table.
Last edited by Deathscythe4722; 09-08-10 at 07:56 PM.