RMF Volume Limitations

Guys,

Trying to understand some basics about RMF (Defender, Nemato) vs. sand filtration for commercial pools. Obviously for the larger volume aquatic centers RMF can have some nice payback qualities despite the expensive upfront cost, but I'm trying to figure out a lower bound where the payback here still makes sense. Have you guys seen any good payback analyses and/or know if there's a threshold on volume where, once crossed, an RMF system actually becomes cost inefficient? I'm assuming the hypothetical pool is open 365 days a year. Thanks in advance!