They are indeed similar boats. The Shadow will be quicker (especially to windward) than the Tiki if you use the bigger rig. The Tiki will pitch more.
I don't like boomless sails it is always so scary reefing with a mainsheet block flapping around your face. Most Tiki sailors seem to lower the sail completely to reef, which maybe OK offshore but not in crowded coastal sailing areas. Tiki mainsails also seem to motorboat all the time as they have no battens.
I doubt if there is much difference in build time or cost between the two.
The Shadow/Strider Club has enough carrying capacity for 6-8 people daysailing, 4 people weekending or 1-2 people for a longer trip. If you need more load carrying than that you need a bigger boat.
My guess is that the Tiki is similar which implies optimism.
The deep mastbeam, higher freeboard and longer cabin make the Shadow a drier boat to sail than the Tiki. Probably there is more room inside a Shadow as it doesn't have deep V hulls and does have a bigger cabin.
I think you need to sail both to decide properly. Of course the Day Sail to Russia video will help give you a good idea of how the Shadow/Strider Club performs as a cruising boat.