Hello, I have one of these lenses, but have not used it much-yet. But it will NOT cover 8x10. I bought mine thinking that I was getting the f/6.8 version but did not look closely enough at the description and got the f/6.3 version. As Tim Atherton pointed out to me, the f/6.8 lens is a factory mounted process lens that without the shutter is an f/9.0 lens. These lenses will cover the 8x10 format and are reported to be great quality lenses(I have a 270/6.8 computar symmetrogon and it is one of my favorites--it covers 11x14!). For 4x5 or 5x7 the 210/6.3 lens is probably very good, as it was made for those formats and did not start out as a process lens.
The Computar Symmetrigon is a different lens design from the f9 Computar that people rave about for its large coverage. The Symmetrigon is a four-element airspaced design, which, despite its name, is not symmetrical. Computar spec'd the Symmetrigons as covering 72 degrees at f22, which, for the 210 mm version is a diameter of 308 mm. So the 210 mm Symmetrigon will probably cover 8x10 without allowing movements.
I am not surprised that the 210/6.3 C.S. is only a 4 element lens. It is light enough that that makes sense. But I can assure you that it will not cover 8x10. Or at least mine doesn't. It leaves the corners dark even when stopped all the way down.