Clarification: I use the term "cage pedals" to mean a traditional flat, metal pedal with serated edges to help grip the shoe, sometimes referred to as platform pedals. I do not mean toe clips. Why in the world would someone try to ride with toe clips installed on one side and SPD on the other side?!
I am indeed looking at the Shimano PD-M324, though the Wellgo WPD-M-17C is slightly cheaper. Mr IGH, have you had any particular problems with the Wellgos?