I for one am somewhat (and increasingly) skeptical of the benefits of clipless.
Pedals don't actually enhance performance the way people think they do. The common assumption is that with clips, you apply power on the upstroke; this is incorrect. All you're doing is lifting your leg. (Keep in mind your leg is not weightless; each leg is about 10% of your total weight.) Even the most powerful pro cyclists aren't adding power on the upstroke. (See
http://velonews.competitor.com/2010/...yclists_137556 for more details) I also have yet to see any power data that confirms the alleged performance benefits of clips / clipless.
My feeling more and more is that clipless is more about feel and preference than anything else.
So I'd say if you want to try touring on platforms, do it. Your feet and legs will be fine, as long as your saddle is adjusted properly. In the absolute utterly worst case scenario, you might be a tiny bit slower; in a touring context, BFD.