I have both.
I don't use my blot powder as a foundation, though. I use it rarely and when I do, it's usually more as a setting powder if my face seems too shiny or it's really humid out to absorb the excess moisture.
If I want studio fix powder to be lighter/sheerer, I use it sparingly with my 187; if I want it heavier, I use the applicator first and then the 187 to even it out.