I personaly would drop all of the pistols and bio ammo from every one. In my oppinion, you should always be FoF, even if you are close enough to charge anyway, so that you can get more models in assualt. Also, you should always be wanting the extra attack.
The Shadowseer looks fine, as does the Solitaire. You should prabaly beef all of your Troupe and Mime squads up with the points you save from dropping the pistols. Maybe exchange the Cannon on the Venom for a Fusion Gun aswell.
I think that the list is a bit small, but other than that, should work quite well. It is quite similar to my 1500 point list that I am making.