Doesn't appear to help! Have HL blades on the bottom & medium/normal on top. Still clumping, only tested on 2 lawns so far but I would say at this stage that its no benefit, I mean some of the grass dispersed a little better or rather its just spread out over a longer distance (as expected), so if that's a benefit I don't know. The clumps still exist, I was getting very small clumps but cutting an inch or less of grass, very mildly damp from morning dew but it was 11am so its not exactly early morning. The clumps when I pick them up and rub in my hands are not wet to touch! Any decent deck should not be producing clumps in the conditions I was cutting! Anyway Ill leave the blades on and have another go tomorrow. Mick I dunno what to say, if I was playing on the team then you would have no chance ... So without me you may win for another how ever many yrs.