I'm planning an India trip in January and will need to get from Agra to Chennai. As far as I can tell, my options would be to either take ground transport to DEL and catch an evening flight on Jet or Kingfisher to MAA, or else take the one Kingfisher flight from AGR to DEL and connect DEL-MAA.
Does anyone have any suggestions of which is more convenient?
If we take ground transport from Agra to DEL, how much time should we allow to catch a late-afternoon flight out of DEL?
There would be about 85min connection time in DEL if I did the connection; is that enough time for a domestic connection?
Is there other air service out of AGR? that's the only one I can find.

Interestingly, Kingfisher's website will only sell me AGR-DEL-BOM-MAA routing, with 2hr connection in DEL. Expedia will sell AGR-DEL-MAA, with 85min connection in DEL. Kingfisher will sell each segment separately, but not together as a connection. Is there a reason that wouldn't be valid?

Thanks for your advice.