I absolutely love the piston system. I do use the for Dual Deploy on the PML Kits with Quantum Tubing using a LOC Phenolic Altimeter bay. They work fantastic. Main thing to remember is to follow PML's Guidelines on Black Powder Charges. It doesn't take very much. I see folks using way too much black powder for the ejection charges. The Quantum tubing is a breeze to clean and makes the piston ejection work like a charm. No chute protector is needed and i even run a Jolly Logic chute release on some of them as well.
First, I want to say that the piston system isn’t for all rockets. Cardboard rockets and dual deploy rockets I would rather not use the piston system. Cardboard doesn’t clean up well, alcohol soaks right into it. However, quantum tube and fiberglass are a breeze to clean BP residue after a deployment. I reiterate, the piston system doesn’t lend itself to dual deploy rockets where the electronics are placed in the coupler; you can’t run your ejection charge past the piston, though, you can easily use the piston system in the payload section to deploy the main chute.