Gear matters, but not that much. Sure, a D3S and a macro lens would take this shot better (quality wise) but the composition, technique, and subject matter are all the same. Just find the interesting things in life. You can take this with any decent DSLR. Sure, a point-and-shoot compact camera can't do it, but an old D50 can.
I've learned the same thing in the past couple years I've gone semi-professional. I've had friends with better cameras than my D3100 (it's not hard ) but they barely know the basic settings or how to compose a shot..which is super frustrating when they're packing something like a D7100 or nicer. So you're right, it's not so much about the gear as it is your knowledge on how to use it right keep up the great work btw!
D7100 blows the D300 out of the water... that's what I would go for. It's just newer and better technology. You'll be impressed by the sharpness of that new CMOS filter. Having no AA filter helps with detail too.
The D300 is a cheaper alternative though, so I understand if it's a budget call.
For me, I wouldn't actually buy a D300/D300S new - my grandpa has one and it's kind of become my dream camera a little bit It's just a great balance of film/digital prowess. As for buying my next body, I'm fairly certain it will be awhile probably a year at the very least..I would love to have the D7100's manual ISO while shooting video, as well as the external mic port and manual bracketing - it's little things like that my D3100 falls short on But I've also heard that there's 'no such thing as a bad DSLR-' which I've found to be quite true (unless it's broken )
I mainly got it for the improved sensor performance. Very good in low light, very true to color and dynamic range. I understand the nostalgic need you have for the D300s though. It's still a great camera!
You can create some magic with the D3100 too. It's all about the subject matter though... finding something beautiful for the viewfinder.
Gorgeous, the lens flare is beautiful and the lighting is really dramatic and eye-catching. The timing is awesome as well, and the yellow stands out really well against the green. Lovely work, I wouldn't change a thing!