My understanding is that gypsum boosts the "temporary" hardness, ie the calcium sulfate count. This is desirable in medium bodied ales... pales and browns, but definitely undesirable for most light beers.
Hardness is complicated, because you can't just call a water hard or soft and leave it at that. The particular ions/minerals making it hard are important too.
Secondary: Sangiovese, Honey Nut Brown, some Pilsner/ale kinda thing that just won't quit...
Tar Sands Porter, Special Dark Bitter,Oaky Red ale, Hammer & Tongs Black Ale, Black Draught, Cooper's Bitter, Baron's Pilsner
Super Saazy Saaz Pilsner Saaz (It's a little green, yet)