Besides shorter range for the 321 and 739, they are both ground loving machines. Very high V-speeds and runway requirements. In Asia most of the runways are long and at sea level. No problem. Europe and N.A. have a lot of old inner city airports with 2000' meter runways, or less. Not good when V1 and Vr are 173 knots.
I think for thr A321 V1 is about 135 and VR about 145 kts.
Depends on your definition of 'just about'. We operate both the A321 and B757 and on the same route, both with max pax, the B757 uses 14% more fuel per pax. Which at today's fuel prices makes all the differences.
Airbus / CFM and PW promise the NEO's will do even better, 12-15%. Also MRO costs are significant lower. That said the 757 is the only 4000NM 200+ seats NB available..