I don't know much about cheesy lists but I think that those wrack units are easy kills in a kill point game and easy kills in an objective game. I guess you could hide them on your backline and use the Nightshield to avoid being shot at but then you are having 420 of your points do nothing for most of the game. I think units of 5 would be better.
I don't think that the Shard is optimal on a Farseer - you only have a single attack on your profile and he's running solo. Perhaps you mean Mantle of the Laughing God? It gives him Shrouded + Infiltrate with the ability to re-roll failed cover saves. He loses Independent Character however so can't join units but can still challenge. I personally prefer this on an Autarch but thats only because I want the Mantle to allow him to play aggresively, rather than used defensively.
EDIT: I also think your Dire Avengers are too small (and easily destroyed), I know you want to take a Wave Serpent as they're considered 'Broken' on the internet, but that, like many things, tends to be when there are large numbers of them. If it was me I wouldn't bother with this unit, I'd take Jetbike Guardians but thats only because I love them so much!
Blasterborn look like they could get badly hurt by following the beast pack; all your eggs in one basket (or small section of the table) comes to mind...
Edit: you could drop 1 wrack venom, swap 2 wrack units for Wyches (leaving you with 1 wrack unit), bump all units up to 5 strong and give the Wyches haywire grenades. Would leave you about 5pts spare.
"An eye for an eye leaves the whole world blind"
Mohandas Karamchand Gandhi