I-4 has nothing to do with spool.
Realistically these motors are VERY different, so much they aren't even worth comparing.
Rod ratio, bore/stroke ratio, compression ratio, cylinder head port symmetry, block strength, combustion chamber shape, charge and discharge coefficients, flowrates, thermal efficiencies...
due to layout of the engine however, they can have quicker spool and an even exhaust pulse much more easily than an EJ. Those are big for comparing the two motors in a street and race application. Their block in OEM form (still 85mm bore) allows for 40+psi boost where as a stock EJ257 is limited to a little over 30 or so. The 4G can run taller lift cams with more aggressive ramp rates. I.E. They can get easy power through lots of boost and big cams.
Comparing stock turbos, the TD05HR-16G smokes any stock subie turbo...but that is a moot point as you're looking for the 600 realm.