Short answer: Keith is right that it does better at colder temps. I'd say "typical" ales temps are ideal for this yeast when making a "typical" strength saison. If you bump up the gravity, I'd drop the temp.
My homebrew club did a saison-themed meeting last summer. Probably 6 or 7 people brewed saisons with 3711. I did an "imperial" Saison that was pushing 12% ABV, most other people were more in the 5-7% range. I fermented mine at 56*F, everyone else was in the upper 70s-mid 80s, with one person up in the 90s. A few of them had more fusels than mine, and a few were more "angular" and rough than mine, but they were all obviously the same strain and had the same palette of flavors.