I have an A400 Xplor - the 3.5 green receiver gun. As to it not shooting light loads, I'll call BS. Mine is ONLY used for sporting clays by my wife (and me when she lets me) and I reload a 3/4oz reload - that's a 28 gauge equal - and this gun has never malfed.
Yes I bought it used, and even then it wasn't cheap, but with the KO, it makes any load feel soft.
If you are truly going to shoot 3 and 3.5" behemoths, this is a gun worth looking at, even if it means saving up and buying lightly used.