I prefer a straight eyed hook for any type of pattern. Pure speculation, but I think down eyed hooks come from a time when the fly needed to be snelled onto the leader, a step up from the spade head. Like snake guides they've become part of fly fishing tradition. Fortunately, for me, most companies that produce "fly tying" hooks have straight eyed hooks for the various styles needed for trout patterns. Once I get into the larger panfish, bass/pike/muskie and salt water patterns I'll switch to conventional hooks, Aberdeen style crappie hooks, mosquito hooks, drop shot hooks, straight shanked worm hooks, jig hooks and treble hooks. Don't sweat it if you don't have down eyed hooks.