I, too, would recommend folding pedals esp. if you need to "fold" them often.
I first bought a pair of
these for my Brompton, and my assessment is that they are pure junk for the price: they rattle and squeak, do not feel solid when pedaling hard, and are slippery.
I then found
these which not only have a better finish, but have a better locking mechanism (though it does protrude out a bit when folded) with a more solid feel, are cheaper, and are from a well-established brand name. My foot does not slip as much on these, and they are lighter, to boot. Both above mentioned pedals are installed using hex keys: 6mm for the Dahon and 8mm for the MKS, if I recall correctly.
The disadvantage to both is that you can't install toeclips or straps, if that is important to you.