Valor line a must for damage guardian?
No its not, you can compensate with gear, but loosing out on AH and MF would be that crucial, unafortunately the entire profession is more or less built around those two traits.
Sure there are other builds that work but i havent gotten anything to work as well since staying alive is the same as doing dps.
Frankly i think Anet should make AH innate, then other/more builds would be valid.