I got the Shimano M540 SPD. I went for a morning ride and was pleasantly surprised. Knock on some wood… I didn’t fall, but was very conscious of stopping and starting. I did notice that one shoe was awful tight; when I checked the sizes I found I had two different shoe sizes.
I have those pedals exactly. For the money, they're pretty nice.
Hopefully you can take the shoes back and get that sorted out!