So I just tested the Betec 50v2 power and SWR with a Surecom SW-102 meter and 2' RG 8x patch cable and connected to LMR 400 to my j-pole antenna. Here are my results across several channels:
Low Power 6.4 watts
Medium Power 24.6 watts
High Power 55.7 Watts
My first test was with a 12' rg8x patch cable and the numbers were considerably lower (eg 38.4 watts high power) then I used a 2' patch cable and got the higher above numbers.