well for me personally cause i dont do track they are perfect for the uk roads. maybe a bit to harsh on the odd occasion, but i do have my dampers set on stiff settings.
you certainly wont be doing any wrong by going for the juniors, easily as good as the best imo.
as for the racing specs, well i've never owned a set but apparently the qaulity is meant to be a better than the juniors, and i beleive the shock design is better to, to cope with the demands of track racing, and have better cooling abilities.
the racing specs also have adjustable dampers, and come with the same spring rates as the junior specs. so they should be fine for uk roads.
at the end of the day it comes to price.