Some ruminations upon G10 straps:
Tan/kakhi looks cool, green is without a doubt tough looking, gray is weirdly National Socialist, blue is for pansies... In the end, I think that black is really the best tactical color for these straps.
In any event, gray and black were offical M.O.D. issued colors. The remaining colors were options if one was inclined to match the strap color to the color of their military-issued briefs
I've been known to wear a G10 (incorrectly called "Nato") strap on my Rolex sports models.
I either wear the black M.O.D. issue with chrome-plated hardware (which is cheaply made but takes on nice patina), or the well-made thicker variant with steel hardware, or lastly, the black Tropic weave version (during hot humid weather).
Only for the 1675 do I wear the leather G10. It is not appropriate for 5513 since it is leather and the Sub is a dive watch!
I do not like the Bond G10 at all (despite the fact that I have a pic of my Sub 'wearing' one).