If a DB & DC plan are permissively aggregated then under the (a)(4) regs does the vesting schedule have to expressly be the same under both plans, or just tested as non-discriminatory on the current avail/effective avail test ? I don't see in the (a)(4) regs where it states that they have to be the same. I would assume though that having only NHCEs in the DC plan and it having a lesser vesting schedule than the DB plan, though still a statutory schedule, would be discriminatory ? any thoughts ?

They don't need to be the same, just tested as a BRF.

Sounds like your arrangement has issues. You could always go for a ruling from the IRS (Demo 3 I believe).