I had the exact same experience.
My SPD clip ins were holed/falling apart and I just couldn't find anything to replace them (I'm picky...)

So I started wearing runners on the bike and really didn't notice the difference. When the runners died, I actually went back to the old SPD clip ins and the difference was amazing, 360deg power delivery was immediately apparent. So now I'm back to my ratty clip ins, with a shoe cover to cover all the holes/defects until my new shoes arrive- A pair from Northwave.