Well Safexpress did not work out. Their lines are perpetually busy and the portal sucks big time.
I ended up using the services of
Avaan Excess Baggage service who specialize in this service and have a couple of outlets at Delhi and Mumbai airports. Rates appeared to be much more reasonable than the flights so decided to book the 30 kg option for one luggage. Pickup scheduling and payment is done on their site and it shows multiple price options (see attached) based on luggage dimensions and weight (you can also choose between Road and Air). The tracking is enabled only after pickup and not after payment. They use Gati. Good thing is that they are pretty responsive on emails and phones. The pickup was delayed by a day but they did call and apologize for the same. The Gati guys handed the consignment note and took the standard declaration. You do have to pack the luggage well and they suggest bubble wrapping. Delivery was pretty quick though, within 4 days of pickup for the cheaper Road option. Overall experience was fine and the customer care called to seek feedback and requested to leave the same on Google.