We've traded for several years now. When we started, DL had a little class for kids to teach them about trading, how to ask for a trade, what to look for etc. We were told then that only the cloisinne pins (the metal with enamel paint) were acceptable for trade. In the beginning, most of the CMs that had lanyards on knew a lot about the pins. They would not accept Sedesma pins.
These days, it's almost a requirement to grab a lanyard at the start of your shift, so as another poster said, many of the CMs don't know much about the rules. They just look for a Disney stamp (sometimes) and just trade whatever you want.
You will be able to trade the Sedesma pins. But you may run into a few CMs who won't accept them. Personally, I don't buy or trade the Sedesma pins. My son even knows how to spot them and won't trade them either. It just doesn't feel right to me. I get plenty of pins off ebay for about the same price as I would pay for the Sedesma, and I'd rather trade the true Disney pins.