Low output on 6 meters

Don't forget that the FCC limits drive gain to 15db for commercial amplifiers and make sure you take this into your calculations. The PGXL is not like your grandfather's amplifier. :)

For the PGXL, the max output is limited to about 62dbm (about 1500 watts). In order to keep the FCC happy, you will need 47dbm or about 50 or more watts to drive it to 1500 and keep the gain under 15db.

As for heat, the Expert amps do not have Harmonic Load management as the PGXL does. In the Expert, harmonics blocked by the low pass filter just prior to the antenna port are reflected right back into the power amplifier and this can contribute to IMD products (aka, dirty signals).

In the PGXL, the reflected energy is trapped by a high pass filter and diverted to the harmonic dummy load so that this energy does not interfere with the PA at all. When your amp heats up, it is likely due more to reflected harmonics heating up the internal 400 watt dummy load. This also results in a much cleaner transmitted signal.

Using MeFFA also allows for a cooler running amp on constant carrier modes like RTTY, CW and FT8.