Ok, now I'm finally in from work, settled down, out of my work clothes, and relaxed, I'll comment on this topic in greater depth than I could when I was on my iPhone 4 earlier.
Whats-his-name, who replied initially, if you've replied again I won't have read it and I'm not going back through previous pages to read another dig.
For the record, on my iPhone 4 I can replicate the issue. However it is circumstantial. Now, right now, any "hater" reading this will be scrunching their eyes up and frowning while gasping "WTF" at their screen. Hear me out, I'm here to comment, not to bitch or get involved in petty arguments.
When I am in my home my O2 signal is, as always, horrendous. Even on my iPhone 3G I was lucky to get three bars and GPRS. I could not, I repeat could NOT, get 3G or Edge in my home for love nor money. The price of being on the outskirts of Glasgow City Centre and on O2. This is the same with my iPhone 4, GPRS and two/three bars at most.
In the City Centre, where I work, the O2 signal is full blast five bars on 3G. This was the case on both my old iPhone 3G and my iPhone 4.
As I type this, I have picked up my iPhone 4 .... three bars, GPRS. I will try to replicate the issue, as I have done before, and lose reception.
Three bars to two bars: 12 seconds.
Two bars to one bar: 8 seconds.
One bar to zero bars: 6 seconds.
So, basically, from three bars signal on GPRS to "Searching" in 26 seconds.
However, when I try to replicate the issue when in a full 3G reception area, it just will not drop a single bar. I have stood outside St Enoch Shopping Centre in the heart of Glasgow City Centre waiting on my wife picking me up, and have stood there with my hand "clawed" round my iPhone 4 trying to drop the signal. Minutes passed, not a single bar dropped.
When in my office, which is notorious for poor reception, I get three bars and Edge on my iPhone 4 and again, I can replicate the issue.
On my own PERSONAL experience, it is circumstantial depending on the quality of the signal in the area you are in at that time.
Believe me, don't believe me, it means nothing either way to me. I am posting to be informative to those who wish information. Haters who have inhabited and taken over this site for the purpose of bitching about anything Apple or Jobs does, will read what they do and see what they want within the words.
That's my experience above, and as I said earlier, I do not "cup" the lower end of the phone deep inside the palm of my hand and never have done. That's not to say people should have a certain way to hold a phone, but it's very much a case of an issue coming to light and people leaping on it.