Your question is based upon faulty information that there is a difference between the two systems and that loose of signal in rain is normal.
The fact is, both systems have satellites at approximately the same orbital positions and altitudes. The transponders (transmitters) in those satellites have the same power output and the dish antennas on the ground are basically the same size.
A properly aimed dish antenna from either company should not loose a signal in anything but the heaviest rain (and I am talking about rain which is heavy enough you would not want to drive in it).
Those satellites you are trying to receive a signal from is 25,000 miles in the air. An antenna movement of a fraction of a degree makes a big difference in signal strength.
When my Directv was first installed a few years back, I had a decent signal but rain would cause an outage.... then I started checking my signal strengths, compared to what they should be.
The fact is, the antenna had not been aimed correctly from day one. I called a tech out and he repeaked the antenna and we have not had a signal outage since then.