Concentric venting for tankless water heater

[Niccio]

Hello, I've got a question I'm hoping someone with more experience in tankless heaters can help with. I'm doing an install of a Takagi 310c series heater. It calls for concentric vent pipe made by a certain manufacturer. Has anybody used pipe from a different manufacturer? It looks like the only difference is the "quick-lock" system they use, but it would appear that any 5x3 venting would work. Short question: could I use Rinnai concentric pipe on a Takagi tankless heater and save a few hundred bucks?

Thanks!