150 is fine, I think, if you want a bit of malt character in your saison. If you want a drier, more traditional saison, maybe mash lower. If you go with the Dupont yeast, most of the aroma comes from the yeast, so I think you're right to be careful with the dry hops. I'd avoid the citrusy stuff, but I wouldn't be afraid of the higher AA hops, depending on the strain. I bet Nelson Souvin would be awesome. Northern brewer might be good, too. Or, stick with a goldings for they dry hop. I'm pretty sure that's what Dupont uses in their seasonal dry-hopped saison and it's damn good. Personally, I'd try a higher AA hops, especially if I mashed at a higher temp. But that's just me. The beauty of dry-hopping is that it's easy to change your mind at the last minute. Give the beer a taste/smell after a week or so in the fermenter and use your instinct.