Thanks for adding the new images at ISO 1000. Looks like there is about a stop noise difference which is what I expected. The D700 ISO 900 and D300 ISO 1400 threw me at first since I thought the D300 image was also at ISO 900 and my eyes popped out but then I realized the ISO was not identical between the two.
Good test shots with useful comparisons.
Albert J Valentino Nikonian Moderator Emeritus Vantage Point Images Mastery of Composition is the Key to Great Photography