The stainless is heavier and denser, but I haven’t tested its acoustic effects. I offered the stainless PVD plates because a lot of people specifically asked me for that material and finish. PVD on stainless obviously allows certain looks that aren’t possible with powder.
The other main difference is that the PVD plates were purchasable separately. My deal with the factory for the Norbaforce Mark IIs is that they come as a set, so I haven’t planned to make the powder-coated galvanized steel plates available separately. I did think briefly about selling the powder-coated separately, but ultimately decided that if I was going to offer an after-market upgrade plate that it would make sense to make it something special and go all out (stainless and PVD), offering it as a separate GB that would ship sooner than the Mark IIs. The NF MK II group buy already has 18 SKUs, which makes logistics hard to manage, and I just didn’t want to add the complexity of selling plates separately on top of that into this GB.
Apologies for any confusion, but FWIW, I did mention this in the GB thread.
I have a creative solution to this problem: make my own plate.