I know others have said these clog up with dust.  My thought is they are using too small of a dust collector for 4 inch lines and just don't have enough suction to keep them clear.  I have never had a blast gate clog up on me.  I have had 6 of these performing perfectly for 8 years.  One broke when I dropped it.  It doesn't look like they changed anything in the design so I expect great service out of the 3 new gates just like the 6 old ones.