I'm on the fence about getting a Drill Doctor... Seems like most people that get one are glad they did and wish they had gotten it sooner. However, I'm questioning whether I'm at a point where I really need one, or if I just like the idea of getting more tools... What do you think, when is a Drill Doctor worth it? Also, which model would you recommend? I don't have anything bigger than a 1/2 inch, but I wonder if I'll regret not having the 750x in the future.