I use both Shimano (but not the 520/530) and Candy SLs on the commuter. I find that the Shimano is more of a pressure ramp-up/pronounced snap in and out, and the CBs are a bit less of a resistance then a softer snap. The tension to release feels a bit less. But sometimes starting from a light, I have to pull up a bit to confirm 'yea I'm in' because I did not feel anything snapping in.
If the issue is generating enough force on that outward heal movement, maybe the Speedplay Frogs would work. They require no effort to get out; just rotate your heal outward enough and they will 'fall' out. I've been intrigued with the design but been happy with XTRs and single release cleats so never tried 'em.
As long as there are no physical issues making that outward heal movement difficult I don't think the multi release cleats will make anything easier and increases the chance of unintentional release. The foot/shoe really needs to move as one, if your foot can move around in the shoe it will make release just that much harder so make sure your shoes are a nice snug fit.
Tzvia- rollin' slow...
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