In reply to goldmember: OK, should be a fair amount of float on those, if possible while riding feel how much float you have either way of your standard riding position, then adjust cleat to suit so you are as central as possible
Stiffness in new springs for release, assume they are wound back fully, spray some lube on them, they will soften with use, other option is a multi direction release cleat, these will release with a firm upward pull too
there is another possibility which is causing you some pain and that would be CANT, sometimes this needs to be adjusted, harder on an SPD but possible on the footbed, try other things first though