I checked the differences in reception for the standard battery cover vs the extended battery cover. I found that with it laying on my desk there was a -1dBm difference with the standard cover being better. But the difference with the device in hand vs on desk was much larger.
standard battery on desk = -85dBm
extended battery on desk = -86dBm
standard battery in hand = -102dBm
extended battery in hand = -102dBm
Conclusion: no difference in reception between battery covers.
One issue I saw today was that in my local Home Depot I completely lost signal. I tried rebooting with no effect, failed calls three times. I've never had an issue getting reception with my iPhone in this store. In Addition, my wife's LG Cosmos had a decent signal. she tried calling me with it going straight to VM each time. This is a problem.
standard battery on desk = -85dBm
extended battery on desk = -86dBm
standard battery in hand = -102dBm
extended battery in hand = -102dBm
Conclusion: no difference in reception between battery covers.
One issue I saw today was that in my local Home Depot I completely lost signal. I tried rebooting with no effect, failed calls three times. I've never had an issue getting reception with my iPhone in this store. In Addition, my wife's LG Cosmos had a decent signal. she tried calling me with it going straight to VM each time. This is a problem.