No, I haven't used them before. I haven't actually made any clamshells yet. I have some from the classies that I'll use eventually. After that I plan to order from Maple Street. I've joined their facebook page, and they seem to have happy customers. I did a search for "clamshells" on there for you, and here are some comments I found:
"I am not sure if it is just me or not but Maple StreetClamshells seem to be thicker and of higher quality than the ones I have been getting from my other supplier. I will order from this company again."
"I got a few tarts done yesterday! Love Maplestreet clam shells!"
"Charlie, I think I have a small obsession with your products!! Everything pictured here is with your products except my logos. Got my shipment in friday and I'm already out of clamshells! Good thing I ordered more last night! (Sorry they aren't great photos)"
"...Made a ton of clamshells a month ago with Charlie dye, wax, fo and containers and ordered mucho labels from Online labels - finally have margins straight (did I mention that for Christmas I got a nice new printer for labels?) and a quality print. Thank you Charlie Libengood and team for great products and service!"
Hope this helps. I'm really not affiliated with the company, just want to help you get a good deal if possible.