Hello,
So after I did the 250mW mod, a lot of guys were very confused about how that little 150mw increase could help you. So, I searched for a way to show the benefits of increasing the output power with 4db (a.k.a 150% increase in power). 4db should theoretically give you at least 50% increase in possible distance.
So I went into a bando, and flew on the floor above me, having a concrete slab between the transmitter and the quad. At the end of the videos, there are 3 charts resulted from the telemetry logs from OpenTX: RSS, RQly, RSNR.
RSS= Received Signal Strenght, RSNR = Receiver Signal To Noise Ratio, RQly = link quality (valid packets).
You can download the logs yourselfs, first flight in the log is with 250mw the second is with 100mw (you can open them with OpenTX Companion)
https://drive.google.com/open?id=1tLbEWMSc5gHHx8vxYf5mn5LxBPNg-Of0
Hope this was helpful in understanding the benefit of having an increased output power.
Thanks!