Mission Fish and Optimum are for deeper water, or working the bottom. You can fish the Mission Fish in grass and stuff because it's so weedless, but you'll probably miss a lot of fish on it. I don't have one because I'm assuming the hook won't stick very many fish because of the way it's rigged. The good part about the bait is you can fish it anywhere. I might break down and buy one in the future just to have something to throw around frog mats, or grass or whatever. The optimum can easily be replaced by a big hammer or fish trap ;-) Same type of deal, but the Optimum doesn't have as good of an action, IMO. The eyeballs fall out too. Read Rob's swimbait article on this website for reference on those types of swimbaits. As for the Castaic, I'm not sure if you're talking about the swimbait or the soft bodied trout. I'll assume swimbait. I've got a 9" one that looks super, but it doesn't kick at all, and it's got a terrible action on the fall. I'd reccommend trimming the underside of the tail to make it kick better. Once you do that, fish it on main points, and all the usual trout plugging spots. Run it by a couple bushes, etc. Now, you made a good choice on the Osprey. That's one of my favorite baits. If you're in the area, stop by Bass World West and check out how they re rig their baits. Check my post on this board too, I put up some pics on how I rig em. Once you re rig em, you can either straight crank em up toward the surface, or you can do a lift and drop deal so that the bait dimples the surface and then falls back down. I think it looks killer. It falls really nice and looks like a trout feeding on bugs. The best way to find out which baits you like best is to try em. I can tell you whatever I want, but until you go on the lake and find out that the eyeballs fell out of your Optimum, or a 13lber spit out your mission fish, it doesn't mean anything. So, mess around with all of em, and let us know how you do.
-Brian