GT is definitely my prime damage dealer, with rapid fire being used to mop up the rest of the mobs HP as its mana costs are much lower. I guess that means I should prob stick with the first bow. I'll give it a go at working it out myself but frankly I'm pretty average when it comes to crunching numbers. Thanks again...
On that note, you may want to stop putting more points in to Glaive Throw. The damage per point goes up rather slow while the mana cost increases stupidly fast. 5/15 is about where it's perfect for spamming (for Focus heavy builds) so more than that will really eat into your Mana.