Yea, mine aren't going to miss but the towers in 'Dungeon Defenders' can.
I also don't see any point in doing collision detection for projectils, until you seriously want towers to be able to miss. All these games I've seen so far never miss, so nothing but the distance of the bullet and its target matters (or even just the precalculated "time til impact").
Just a quick reply as I'm at work. I understand the don't fix it if it isn't broke argument, but I really want to establish my limits now so that I can incorporate that into the design. Sure, it'd never be a problem if this was a single-player game but I don't intend it to be. I wanna see what kind of limits I can push in terms of scale, i.e. How many max players a server will be able to handle with it computing all the logic server-side.
Obviously, that's a long-term goal but I like to be well-researched in the meantime. I'm going to write multiple algorithms anyway and compare them. I plan to post my code and results on here once I've done a prototype.