If you're using SPDs currently distance isn't an issue. All Shimano touring pedals are SPDs. You get more side to side twisting movement (float) with SPDs. It's lack of this that knackers knees. Consider swapping to a touring pedal if you want a larger platform to push on but potentially keeping the same shoes. I say potentially because some MTB shoes have chunkier soles meaning they won't fit touring pedals.
If you want to change. I've used Shimano pedals and shoes for years and rate them. The float adjustment is in the cleats. Yellow = most float.
If you need to walk any distance stick to SPDs
