For now, both Propins & Sedesma are 'ok' to trade with CMs, but fellow Guests, as always, are free to trade or not. I personally do not usually like either the ProPins or the Sedesmas - the metal is much thinner, the colors are just painted-on enamel (as opposed to cloisonne or cloisonne-style). Since these pins are of thinner metal, they will break or snap more often than pins bought at Disney outlets - the parks, Disneyshopping.Com & even the (Children's Place-owned)
Disney Store.
As long as a metallic pin says "copyright Disney" or "[copyright symbol] Disney" on the back , it is still street-legal for trading with the CMs. Be aware, however, that CMs do not always know the rules and folks here have sometimes run into CMs who have refused ProPins/Sedesma trades.
And WDW is always changing things, so who knows... I'm not sure how they would enforce it, but they could always sever their deal with ProPins and/or Sedesma and drop these specific companies' pins from "allowed-trades".
If you're looking for pins to trade, DisneyShopping sometimes has GREAT sales (sign up for their e-notices) and they will let you stack discount codes. I've gotten Limited Edition pins for about as little as $3 or $4 each sometimes. Also, if there is a Disney Store or a Disney Store Outlet near you, they sometimes have some pins on sale as well.
agnes!