Is MTS Diluent 2 Plus really necessary if the EDTA sample tube is used?

[Clarest]

I was trying to look into the difference between the MTS Diluent 2 vs. 2 Plus and found that 2 Plus contains EDTA to prevent complement activity and hemolysis in test procedure. However, if a sample collected in EDTA tube is used, the calcium has already been chelated in the sample tube. Is it still necessary to use the diluent 2  plus that is formulated specially with EDTA?

In addition, let's talk about the use of EDTA sample tube vs. observing hemolysis as a positive reaction. If an EDTA sample is used, theoretically, we should not be able to observe hemolysis as no calcium is available for the complement activity. Please feel free to share your thoughts.

[RRay]

I have recently learned that in these forums it's best to include if you want theoretical information (fun to think about) or something that is compliant to any applicable standards and is feasible to implement.  Haha!

I'd love to get rid of it too, but hard to justify since it's part of manufacturer's inserts and the Vision won't run certain tests without it (unless I suppose you fudge a barcode and include an alternate diluent).  It's part of the FDA approved system.

I'm assuming the differences between the two diluents are for their specific uses in the system.  Dil 2+ is for your red cell dilutions used for ABO/Rh.  The Dil 2 is for your DATs and auto controls.. I can't remember which it uses for XM, maybe 2+?  The EDTA added makes sense in that regard, but yeah... I think safe testing can be achieved without specialized diluents.