As a N-series user, i choose AP set, and im not really look into AP set or Zitron set, i jz hope that im lucky enough to get a hand set in tip-top condition w/o any software defect and again hope la, these hand set wil last for few years b4 i sell/upgrade it, well guess wat? High-end phones owayz got minor defects, im jz conclude that mobile phone technology stil far away to meet my expectations. Stability? Mayb stil need few years to study..