My main gripe with the Perfect 16 is that it doesn’t do any of the multi gas stuff ( https://www.iqair.com/room-air-purifiers/gc-multigas ), and is more like running a HealthPro ( https://www.iqair.com/air-purifiers/healthpro-series ).
https://leesheatingandcoolingservice.com/wp-content/uploads/...
The 216 filter has 0.17" wc of initial pressure drop at 1000 cfm as compared to 0.12" wc for its MERV 13 equivalent, the 213. You can just swap it in if you started out with MERV 13 [0] have 0.05" wc of extra pressure budget (and an existing compatible housing), and you can probably save 0.05" wc by just changing your filter more often. Or you can design something like this into a new system, just like you would have to design a Perfect 16 in.
[0] You must have some kind of return air filter to avoid destroying your fan coil. MERV 13 is somewhat of a baseline for a decent system.
https://www.iqair.com/us/whole-house-air-purifiers/buy
That’s… a lot more expensive than Aprilaire for only slightly better performance. Two or three Aprilaire (or Lennox, etc) filters in parallel will dramatically outperform the Perfect 16 and will cost much less. Of course, that would require some custom sheet metal, but the Perfect 16 may also need some custom sheet metal.