I like defilers because they are big and scary. If my opponent ignores the defilers, they will be dropping
str 8 pie plates that role 2
d6 to penetrate vehicle armor. That's a 50% chance of penetrating a land raider if I get a direct hit. So I'd say defilers are pretty decent supporting fire, not as good as obliterators, but defilers are a better distraction. Also I like defilers because they can hang back and take out enemy deep strikers or out flankers which is really handy. And lastly I like defilers because they fit the fluff for Abaddon, as Abaddon fashioned defilers himself

.
Heavy weapons aren't really recommended on
csm squads because they highly reduce the squads mobility and disables the squads ability to assault effectively.
Good question about the lesser daemons. I have them pretty much because I think they are cool and I like the paint job I did. If anything, they are a cheap troop unit that I can bring in to support any squad that needs the help. But yeah I'm thinking I'm not really making good use of the number of icons I have. I've got icons on Abaddon, Kharn, Khorne Berzerkers, and both
csm squads. Although, the icons on Abaddon and Kharn come automatically, and the
IOCG I have on the
csm squads are very useful even if not used as a homing beacon. I would keep the
IOCG's even if I wasn't deepstriking. Although the personal icon on the Khorne Berzerkers is questionable. But not that big of a deal for only 5 points.
But I think you're right, I might need a Land Raider for Kharn and friends. 2250 pt game maybe? XD