Buy the skimmer you need for your next tank, not the one you have now. I have an ETSS 800, rated for 6-900gph for a pump.
Recommended for 180-400g tanks
I have heard that everyone (?) tends to overrate the capability of their skimmer
I have a 125g show, 75g fuge/frag, & a 40g sump that is usually a little over 1/2 full. so ~220g or so
Con: (maybe on all skimmers?) is getting it dialed in right
An in-sump skimmer may be better in case it overflows.Moe had the 800 & had an overflow & it caused a problem
not sure of all the pro's & cons