surely the D7000 is more up to date and seems to be at least as relyable as the d300s (both shutters are tested upto 150 000 releases, both weathersealed, both feel extreme tough in the hands). The two card-slots (for example one main and the other is backup) may help if one card breaks up. The iso-Performance of D7000 is really good. Taking good photos @ ISO 3200 or 4000 in a church (without flash) is one of the advantages of the D7000.
If you are upgrading from Nikon-entry-level you will feel more comfortable with D7000, because the handling (buttons, settings, mode-dial) are very similar. It seems to me, that Nikon combines "entry-level" and "pro-level" elements in the D7000. The "shutter-mode-dial" (single, continous-slow (Cs), continous-fast (CH), silent (!),...) is similiar to the pro line.
Btw. the D7000 has a "silent-shutter"-mode, which maybe is interesting for you.
I personaly changed from a d70s to D7000, which took probably 30 minutes. (ISO-Button is nearly the same, etc, shutter-mode is easier to reach: "silent" in church, changing to CH to get the couple exiting the church)
The D300s is still a good camera but i think the D7000 is better in many Details.
some examples (17.11.2012 and newer, the "older ones" ar taken with the d70s):
http://wuerzburg.nightfever-online.de/?i=248/
hf
