Airtel EDGE as backup broadband?

[johnnycab]

I am after a temporary connection lasting for a month in Delhi. I have already posted here: https://broadband.forum/broadband-india/17543-broadband-delhi-one-month/

But, just in case it takes a long time to get activated on MTNL I am considering Airtel as my backup plan - using it to browse & pickup email on GPRS/EDGE using a Sony Ericsson w810i via Bluetooth on my Laptop. I have read on the forums that transfer speeds vary between 5-25kbps which is good for light browsing and email , Please can anybody tell me:
[*]How reliable is the connection?
[*]What is the best Prepaid package for unlimited GPRS/EDGE usage?
[*]What is the coverage - obviously I start paying roaming charges, as soon as I get out of my chosen city? e.g. can I take it to Rajasthan and get similar service?
[*]Any shortcomings of using this as a main short-term/extremely light-use mobile connection?
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[rageaddict]

i use it as a backup too but at most times it proves as unreliable... meaning my phones battery works for 3-5 hours at the most while surfing... way to much constant disconnections... fluctuating speeds... etc etc