Mids 1.704 (DB 17.90416)
I've placed 6 different IO sets that give +5% run speed. Mids is showing that all 6 count, rather than capping at 5. The sets are:
Aegis x3 - "5% RunSpeed"
Performance Shifter - "5% JumpSpeed, 5% JumpHeight, 5% FlySpeed, 5% RunSpeed"
Gaussian - "5% JumpSpeed, 5% JumpHeight, 5% FlySpeed, 5% RunSpeed"
Kinetic Combat - "5% RunSpeed, 5% FlySpeed, 5% JumpSpeed, 5% JumpHeight"
They all have different descriptions in the set list, but in game they are all "Large Improved Movement Bonus". As I understand it, that is the text that is used to determine the limit of 5 identical set bonuses.