Regarding pressure drop, the curve is in the third page of the manufacturer's brochure:

http://www.proteusind.com/500/500DS.pdf

There's two versions of the meter, being the one the OP is using the one with the highest flow rating (4.5 gpm) and the lowest pressure drop.

It curves from 0.75 psi @ 1.5 gpm to 2 psi @ 2.5 gpm.

The Fuzion (I had to go for a less restrictive block to make the comparison this time, because apparently when talking flow meters, the restriction is inversely proportional to the amount of money you fork out on the purchase) curves:

From 1.5 psi @ 1.5 gpm to 3 psi @ 2.5 gpm.

And the MCW60 curves:

From 0.75 psi to @ 1.5 gpm to 1.9 psi @ 2.5 gpm.

All these have been extrapolated from the graphs published by the relevant manufacturers.

So, restriction-wise is like have an extra MCW60 in your loop.