I know the general consensus will be the SB-900, but at over twice the cost I have to question its true real life benefits over the SB-600. For a non-professional will the SB-600 suffice? I guess I should know, since I've had a couple (along with the SB-400). But I never used it (SB-600) enough to really judge its performance. I still have and enjoy my SB-400 which serves it's intended purpose, however there are times I wish I had a little more power and flexibility in my shots (such as off camera without a cord). Next, with the D300s - would it be possible to use my popup flash as a catch light along with the SB-600 or SB-900? Last question regarding this, does the SB-600 have enough power to use something like a Gary Fong Light Sphere?