My disclaimer to this post is that I'm fairly new to drifting too, and I really don't have any personal experience with a d-box. I'm sure people will have different opinions.

I know it's not what you're asking, but I would recommend learning to drift without the d-box. I drift a nitro too, and part of the fun is learning to control it. I suppose that's easy for me to say because I bought the HPI RS4 Nitro Drift RTR. The d-box really kind of drives the car for you a little. It's made to balance throttle and steering to keep you in a drift with less effort. It's definitely a faster way to a nice clean drift, but (personally) my favorite part is learning to balance that on my own. Of course...I probably crash a bit (lot) more than someone with a d-box, but it's all part of the fun for me!

I'm sure a d-box is nice to have, but I decided not to go that route.