I was recently sent a pair of pedals to test out. I think the only reasons I was sent them was that they have them in orange, I had mentioned that I saw a pair of flat pedals on a Brompton and I quite liked the look of them.
They are Nanotec by a company called Superstar. The are made out on an aluminium alloy and weigh at about 450g so pretty good on that front. They are about he same length as the Brompton pedals and the same again in width. They therefore provide a very good platform for riding. The addition of several studs which can be replaced provides a very grippy surface.
Having them on does of course compromise the fold on the left pedal but dare I say it, they are pretty good! Riding with them on does provide a great deal more grip than the Brompton pedals. I suspect the bearings are better too as they spin with little resistance. In fact these pedals scored very highly when reviewed against others costing more than double the price.
I am not sure I'd keep them on my Brompton but...I like them. They have a very thin profile and I can imagine that on one of my longer, epic rides they would be über comfortable, grippy and easier to pedal.
There is of course only one caveat. On a Brompton I do find them a little vulgar. They are more suited to meaty mountain bikes or BMX, not an elegant Brompton. If they were of similar dimensions to the Brompton pedal and in some way folded or had a quick release mechanism, I suspect I'd like them more. For the meantime I will stick to the tried and tested Brompton pedals, which although not perfect, certainly feel right on a Brompton.