Did you have the iPad baseband? If so follow these steps this is how i fix it:
1) Use cydia to instal SAM even if you activated with official sim
2) De activate phone with sam
3) Re-run redsn0w b7 or newer JB with nothing checked- Redsn0w will hactivate and apply the fix during hactivation
3) De activate with sam
4) Re-activate with itunes and official sim or reactivate with sam.
I followed the steps (I used redsn0w 0.9.10b3) and haven’t lost signal since. So far so good. Like you said, hopefully they fix this in a later version of redsn0w.
Cydia repository for SAM:
http://repo.bingner.com