I understand where you're coming from. To the point about being a sponsor, Nathan also recently donated to the club as well for the upcoming raffle. So there's plenty of room for other players in this industry.
I have also use RN btw. Their offering of live culture grade species is limited though. I've tried both Reef Legends and RN live products. The density of the phyto and pod cultures from Nathan are much better.
I have tried their blended phyto bottles. I bought their package at the last CFM. Their product is a one and done bottle. Dump it in and it gets used up. I also tried their rotifers. Both of those definitely benefit your tank and inhabitants.
I'm not sure what a monthly one and done dosing will do though. I feed my tanks live phyto and tig pods almost daily. Sometimes a couple times a day. If I only did it once a month, I'm not sure I'd notice any discernable difference. If I was in your shoes, I'd order enough of something that you can use at the very least a few times a week.