Just an obversation.

I use all 1/2" tubing.
I use dual DDC+ pumps.
I use 1/2" fittings on all blocks and radiators.

I use D-TEK Fuzion with 4.? nozzles.
Doesn't the use of the Fuzion with said nozzle impede my flow?
If so, why buy aftermarket pump heads to deliver more power and provide more resistance? Wouldn't I be better off using standard 3/8" DDC+ stock 3/8" fittings and tubing?

Seems to me this is the question yet to be answered.

I'm no flow expert but it seems flow will be restricted to the least "flow capable" block. Is that not the case ???

If true, why does 3/8 or 7/16 or 1/2 inch tubing coming off a DDC+ make a difference.

Matter of fact, why do the DDC+ pumps fail ???
Could it be the resistance in the loop ???
i.e. shoving water through a 4.?? nozzle ????

Just a thought.