>It will be a long overdue upgrade from solid DX body, like >D300/s. Quote<<<
If is a Pro Body you want, buy a D2x, D3s,or D4. They compare like a tank to a jeep. But, there probably will never be another DX Sensor in an F5 body, so, you better hope the D300 replacement has a better body instead of being a D7100.
Personally, I have no problem with Plastic or FX. I would gladly take a D5100 with a D3s or D4 Sensor in it.