F900/3 or F900/R do not upconvert ever.
The CCD imager is 1080×1920 and you get obtain a full raster image when recording to an external HDCAM SR vtr.
Reason why clients might request F900 over HDX 900 could be based on an established post production workflow.
Comparing the F900/3 to the HDX-900 is sort of like comparing bananas to apples.
Yeah the both are fruits but each has a unique “taste”.
Hypergamma in itself is a major plus on the F900/3 similar to the concept of film rec on the Varicam.
FYI depending on which version of the varicam you have the HDX-900 will most likely be cleaner in signal to noise especially in the low end of the signal. The Varicam F and lower models are a major dissappointment in terms of the noise floor. One major reason why the 27H had the dark compression vtr feature added.
Tony Salgado