I have a Photon and an Evo 3D. I installed an app called signal status and compared the two phones in my daily use. They seem to run within a couple dBm of each other with one major exception, my Evo 3D seems to have a much different threshold for switching over to roaming or showing no service available. The Photon will be steady as a rock, making and receiving phone calls while the 3D will be to busy deciding what it wants to do switching back and forth.
The Evo 3d's signal is garbage. That's the reason why my wife's 3d doesn't last long like its supposed to, that's why I'm trading my Evo 4g in towards the Photon when my upgrade comes in 69 days. Can't wait.
Yep, EVO 3D signal sucks. I had one for about 60 days and returned it to get a Photon. The Photon signal is MUCH better. In my apartment the Photon has never roamed or dropped a call, while the EVO 3D would roam and drop calls constantly. Not only that, but the EVO 3D wouldn't get a 4G signal at all here... but the Photon gets one right away.
And yes, I noticed exactly what you said. The Photon will hold a Sprint signal, while the EVO 3D is fickle. I've compared the dbm too, and it's hard to tell a noticeable difference in the numbers. But in reality, it's night and day.
When I first bought my EVO 3D I noticed immediately that it's signal strength is total JUNK!!! My Photon gets MUCH better signal and stays connected to 3G & 4G while the 3D does not. It's so bad that I think the 3D should be recalled or refunds issued. As a "phone" the EVO 3D is not your device. But if you need a cool looking paper weight the 3D fits the bill.