At what temperature Mic? Because I use a 5' line too, but I'm at 10 or 12 psi of CO2. I'd think that unless your beer is super cold you'd have to dial the pressure so low that the beer would be pretty flat pushing with beer gas.
To be honest, I've never measured the temperature. I'm not gonna change the temp based on beer style. I also use a CO2 regualtor, so not sure if the reading is right. I do have to turn it up a bit as the keg empties. I just adjust the pressure to a good pour, and RDWHAHB.
(sorry, not much help huh?)