Honestly, I LOVE ASM.
My 180 reef has an ASM G4 (rated for 350 gallons) and a SWC 160 (rated for 130 gallons or something)
My 180 FOWLR has an ASM G4X (rated at 450 gallons)
my 125 reef has an ASM G4. (again, rated @ 350 gallons)
I tend to also overskim but I like to keep my tanks stocked to the brim full of fish and LOTS of skimming is one of the tools in my box to allow me to do this.
Also, I bought each G4 for $200 used (including shipping) I found them on craigslist, and paid the people via pay pal and got them in the mail. A bit risky but worked great. Did the same for the giant G4X (looks 2x as big) but it was $300 used. All of them work fantastic and I have never had issues. Great skimmers.