D300 is a semi-pro camera – do u think you'd get the most from it? Or would a D90 be 'enough'?
It's a decision based on many factors at the end of the day including: budget, features, intended use, bulk, weight, weather-proofing, brand loyalty etc…
I went for a D80 a few yrs ago after considering a Canon as well. I also debated paying more for the D200 but couldn't justify it.
For me the D80 is great – only things I perhaps 'want' are better weather-proofing & higher fps continuous shooting.
Coolhandluke – please contact me with details of your SB800 – I'm thinking of getting a flash in the next week or so. My e-mail address should be in my profile.