I have a Bixler 2 with APM 2.5 and 915MHz telemetry. It flies really well and I've never had any problems with it. However, I've never flown it particularly far away from me. I have tried to do a few surveys on auto mode recently, and the telemetry cuts out at about 300m away from me. I then ran over to the plane in the air (on auto) and it didn't regain signal. Later on it did once it was coming in for landing.
The telemetry logs (attached) show that the noise is always fairly low, and it's the rssi - both air and ground module - that drop sharply, not related to distance.