Primary reason for purchasing a Realta based processor was the superior quality of the de-interlacing. Primary reason for purchasing this particular VP was the large front panel alphanumeric display (negating need for OSD) and the comprehensive collection of input types, including HD-SDI. The SDI input is spec'd to handle SMPTE 292M thru 259M-C (up to 1.48 G/s), so it should handle a VC300 output. Incidentally, the SDI input is not an afterthought as with the other popular VPs but is actually part of the motherboard.
With respect to the chroma question, there is no manual adjustment for chroma offset that I'm aware of. They do have a CCS (chroma crawl) filter, a CUE filter and an ICP (interlace chroma) filter, all of which I normally leave ON. I don't ever recall seeing any program content where it appeared that the chroma was offset so maybe I'm just lucky or these filters automatically take care of the problem.
I might add that this VP has a very noisy fan so I installed my own, to get rid of the noise.