Just my 2 cents... I work at a dive shop that does gas blending. I will let you know that if your tank is not O2 cleaned, a dive shop won’t (or shouldn’t) fill it with any Nitrox blend. Your tank will need to have a Nitrox VIP and the sticker to match (should be colored different than a regular VIP). As for the regs, I would make sure that when you have them serviced, they use the proper lube on the seals (most do anyway). The new stuff on the market should be ok for mixes up to 40% as is. It’s always good to make sure though as this IS life-support equipment.