There is a "modded" RS250 for sale locally. What are your thoughts on this skimmer? What size range tank would you recommend it for? I'd rather ask people who have used it than trust the manufacturers numbers.
Which pump does it come with? They come standard with the Gen-x 6000 but can be upgraded to the Eheim 1262. They are very good skimmers, especially if it comes with the eheim. How heavily will your tank be stocked and with what?
I have the RS100 on my 65 and love it. Id figure youre good to 150 or so on the RS250. Lightly stocked or FO a 180 might be fine.
Gate valve mod just makes it a little easier to fine tune the water level in the skimmer.