I keep larger and mid sized FW preds and will soon move into frogfish and venomoues SW preds, though will try the FOWLR as a mostly LR, skimmer and macro filtration, as my plan is to avoid water changes.
I find wet/dry works fantastic and have converted both sumps to run it, one sump feeds two tanks, the other the big 6x2x2 (though this one needs remaking as there is not enough capapcity over the drip tray and as such it keeps overflowing...). Both set ups have filter floss needing cleaning 3 times a week due to the amount of detritus it removes, far more than I ever saw with submergedx media.
I know I overfeed, and overstock, and have absolutely no ammonia or nitrite issues at all (thought he 6x2x2 has an 11x13x13 trickle tower with two sumps 24x14x12 stuffed to the gills with alfagrog, so i reckon it would just about cope with a basking shark...). I have to water change a little more often than I would like, mais c'est la vie.
With the nitrates, I think that bad maintenance causes it, and these horror stories are repeated; leave a load of crap on the filter floss and it will break down to nitrate (and other elements such as phosphates) which a reef tank will not like at all.
But, how can the wet/dry create more nitrates when well maintained? It must be treating the same amount of ammonia that the LR would be. Therefore, for the nitrates to be evident when there is a wet/dry, and not with LR, means the LR is not processing the ammonia or nitrite as quickly as the wet dry. Now the only research I have found on nitrates for marine fish is that 100ppm is the level above which some detrimental effects are seen.
I know which I would rather have present in my tank out of ammonia/nitrite or nitrate.
However, as the wet dry was seen as a saviour to all, too many set them up, and just left them, thus casuing a nitrate factory (just like overfeeding).
I would love to try an algae turf scrubber on the large marine pred tank, but getting info on them is not easy. That and the bucket system is likely to be noisy, but if you get it working well, it replaces the live rock and the skimmer. Which is fine by me!