Vis a vis reliability, that shouldn't be too bad an issue; the Bx16 doesn't really have too many places where a driver could lose time, except in Fordham...and not every trip needs to run to Fordham; certain trips could run Norwood to Pelham only, or Norwood to Woodlawn only in the rush, and then deadheading back to Norwood.
The current Bx16 route is 49 minutes at its worst; the extended route would still make it only about 55 minutes Norwood to Pelham and about 70 minutes in all over the full distance. Fewer buses would be needed.