150 -180cm brolly - too big for 1-2 speedlights ?

my only experience in light modifiers for speedlights (besides bouncing) is with some 60-80cm umbrellas.

Now i intend to soften the light and try to get more than "head and shoulders" covered, so i am thinking at a walimex brolly.

Do you believe that a 150-180 cm brolly will be too much for 1 or 2 sb-800 ?

http://www.amazon.de/dp/B008DCOY1S?m=A3JWKAKR8XB7XF&tag=idealocom&ascsubtag=JYsXm2VsThZJZmeEsDy78g)

thanks.

--
Please forgive my grammar but if you find it inconceivable address me in romanian.