Knight-suits do belong in an Exodites list, though in a supporting role; IMO the main focus of an Exodites list should be Exodites and their different types of dinosaurs.
I think an Exodite army deserves to be its own separate force, just like the Craftworld Eldar or Dark Eldar are, one that should not need to borrow troops from other sorts of Eldar any more that the others do. Corsairs / Eldar Pirates could well have a place in their own list one day, one particularly styled around them, but this really is not the place for them. Neither should an Exodite list include CE Guardians, War Walkers, vehicles, titans or anything of that sort – if they’re to be given justice to and done properly everything should be new.
Incredibly rare they may be, but I at least have a good collection of Exodites and am actually in the process at the moment of putting together a large all-Exodite army (originally intended to be 3-4k but now going for 7,000+ point). Models are GW only and with the exception of the existing knight-walker and dinosaur models I am converting all other units, often extensively and am including various kinds of dinosaurs, right up to War Engine and Titanic sized ones.
I have thought out tonnes of ideas for the Exodites already and plan on putting together a booklet for my own Exodites in the style of Swordwind by the end of the summer, ideally full colour and complete with unit datasheets and army photos, background, stories, etc. I'm going very into creating models and background for them, however most or perhaps all of the time ruleswise I intend to play with them using the Biel-tann list, with the entire army using the ‘counts as’ rule and various units not making use of the skimmer rule where Exodite model-wise it would be inappropriate.
I had wanted to hold back from posting pictures till I had a few core units painted up, at which point I'd start a painting log thread. Since this has come up I think I'll post up a WIP of the army thusfar (bear in mind this is the early not got all the parts and blutacked together stage):
