by nature economics is a scoring subject like if they have asked about market equilibrium with reference to IS LM curve and you have precisely and exhaustively described every thing then there is no reason that you won't get marks...Economics is a rational choice...
Now the fact that Economics is not a scoring subject remains there but i am not settling on it...Reason: only a few people opt for it and those who opt unfortunately could not get best out of it just because they did not do justice with the paper thus created perception that Economics is not a scoring subject, atleast we have only that basis to decide whether a subject is scoring or not...
SO if you think you are good at Economics after seeing past papers, i would advice you to go for it...