I guess I have been fortunate ,been using closed manifold ,under and periscope over for two yrs ,plus have had no issues ,final dry wall bag ,eliminates any dust getting to the shop vac bearings ,and being out side helps keep unit cool . collecting at the source of the dust at all times ,seems to keep the pressure and the rpm's constant ! May fail tomorrow ,but I doubt it . keep tinkering ,streamlining ,just added small mirror to light up bottom load lighting ,big help seeing starter holes ,that was an issue ,no more ,all keyed on single swing .I love the total dust free capabilities of this arrangement .and ease of use ! Mine is a 788 but I feel could be done on any modern saw ,with same results ! What ever ,works for the conditions and needs you have ,is what works best for you should be used ,I just can not handle the dust !