NZ*G also gets you RU vouchers to use on NZ flights. If your international flights won't be on NZ metal and ticket (and then you'll also be behind Plat/KB for upgrades), then your KFEG is enough for domestic lounges.

Otherwise, PPS points only accrue for SQ J/F flights, so you won't get PPS accumulation on NZ J

so perhaps the other question is, do you get more out of APD or Krisflyer miles for the mileage earn