Hi Mutt,
Yes we do use FMC V speeds during normal Dry Runway Balanced Field operations. Wet runways, unbalanced field (not too many), Assumed Temperature above the environmental limit, and CDL items come from paper V-speed tables.
Like yourself, it's normal policy to use zero wind with the Captain's discretion for use of any Headwind component. Naturally, the worst Tailwind MUST be considered.
FMC speed use is limited to agreement within 3 knots of the Airport Analysis speeds. I don't like it at all, but accept that some (not all) of the possible 3 knots arises from establishing RTOW from "worst case" data blocks in the Airport Analysis, and using actual environmental conditions within the FMC. Also a bit more because the ATOW is rarely right on the Airport Analysis data block limit, but the problem is, "OK, I can understand where this possible 3 knot differential is coming from, but I can't verify any of it in the cockpit"
Then we can get down to obstacle effect upon EOL whilst ADSR is not affected, or interpolation between data sets when multiple obstacles exist.
I don't do the Performance Engineering for my "own" aircraft, the B777. I do it for other aircraft. For the aircraft for which I'm responsible, most of the work is unbalanced field, and paper V-Speeds and RTOWs are available for all operations, Dry, Wet, Balanced/Unbalanced, Anti-Skid Inop, Reverse Inop etc., it means a few more kilos of paper to carry, but it puts me well inside the comfort zone. For these aircraft I've written into policy that for Dry, Balanced, no CDL operations, acceptance of FMC speeds within 1 knot is acceptable. That's because the paper speeds are calculated for QNH=1013, whilst the environmental conditions entered into the FMC might just nudge the speeds by 1 knot. Also exact halves are rounded differently for V1 and Vr/V2, e.g. V1=140.5 is rounded down to 140, Vr or V2=140.5 is rounded up to 141.
How is your new South American aircraft? T'would be interesting to see the manner of data preparation and provision from south of the Panama.
Regards,
Old Smokey