Should I;
Get m520s or r540s with these shoes?

Main concern;
I initially thought the double sided SPD would be good for engagment, but is it that helpful?

Additional information;
-I commute to work 3 miles each way, and I change into uniform at work. If my timing is right, I don't have to stop at all on the way.
-I will occasionally have to go out to appointments and changing out of uniform/shoes is not an option. Through the googles, people ride on their clipless pedals with regular shoes and have not exploded, and if I'm in uniform I'm not going to be hauling ass anyways, and I run a front brake.
-Not really fond of the a530 because the base is wider and would increase the chance of pedal strike.
-I know walking in cycling shoes is a chore already, and a road shoe with a metal cleat would be even more challenging. Possibly get SPDs + pontoons?
-On weekends I go on longer rides (20+ miles).

Are there other factors to consider when choosing?