I’m using AT#SGACT=1,1. I was was using AT#GPRS=1 and I agree that using SGACT gives much better reliability.
I’ve found the AT#SERVINFO command which tells you the exact signal strength and the GPRS status of the current serving cell.
I recall reading somewhere in one of the thousands of pages of information from Telit that using the AT#SERVINFO and AT#MONI commands are preferable to using the AT+CSQ command (Due to the +CSQ command doing a network poll whilst the #SERVINFO and #MONI commands perform the poll as a background task every 3 seconds and so they don’t block your application)…of course this is from memory and might very well be wrong.