Is it going to be purge the alien and scouring every game or randomized? because if it is I'd think about dropping two troops (probably the wyches) in favor of another squad of bikes or a beast pack. Effectively turning 4 VP into just 2 VP and only losing one scoring unit. Just in theory. Otherwise the list looks fine.
Keeping the list mostly in tact I might add a flickerfield to the kabalite boat and grisly trophies to the wrack/haemonculi boat at the expense of the arena champion. To me, assaulting with our bikes is something you usually want to avoid. It can be tactically a good idea, but generally they're more effective turboboosting to kill infantry, and would never assault after using their heat lances to pop a vehicle.
"Excess, yeah that's what we do best."