The 75 a abecs reduce the rattle on my board DRAMATICALLY. I swapped 83mm clones for 83mm Abec 75a, and its like going from BLDC to FOC in terms of noise. Ride quality was markedly improved. The abecs cost about $40 more but I think they are well worth the expense.
Here are some fotos of the weight. The abecs weight 6g more each but its a tiny sacrifice in weight for the improvement.
for anyone in the UK I got mine for £65 (shipping was £3 extra) from: