Did this last week in deciding which to go with when at dealer to evaluate primary V6 manual choice; was (!) diehard manual driver, as was wife, prior to comparison.
Some differences noted:
1.Typical less smoothness of i4 motor idling and under acceleration-minimal
2.DCT shifting slightly slow on upshifts when in tour mode with leisure driving; quicker with aggressive acceleration and quicker yet in sport mode
3. Acceleration much snappier lower rpm for i4, but V6 catches up in higher rpm range and essentially same.
4. Exhaust pops/crackles more prominent with i4.
Was impressed with I4 acceleration, crisp shifts up and down under load; and......i4 DCT chosen, hopefully near future. Just my 2 cents...........although, still not 100% convinced