ESA,
For your cable run of 125', I personally wouldn't opt for the added expense of the quad shield cable.
I have used both quad shield and standard RG-6 cable for roughly that distance (120' - 140'). I didn't observe any problems, even with a motor in the circuit. However, when I tried to run a line that was 185'-200', I started having trouble operating my motor and that was even with the quad shield cable. I had to go much further than this, so I knew this cable wasn't going to cut it. I ended up with RG-11 solid Cu center conductor cable at a run of somewhere around 285'. I use no signal conditioners or amplifiers.
I believe that the quad shield cable is more applicable if you have to route it near AC electrical conductors to help cancel any EMI from the AC power from being induced into the satellite cable. After using both types (standard and quad shield) for the shorter cable distance on my own satellite installation, I can vouch that it isn't necessary to get too gung ho with the cable, as long as it handles the frequency of the satellite signal from the LNBF it will be fine for that short of a run. If you were to get into much longer cable runs, I would be pondering the solid copper center conductor cable instead of quad shield or maybe both options. Then, if you get into really long cable runs, I would go with RG-11 cable and solid copper center conductor.
Here is one tip that I found along the way. If you always use the same IRD (receiver) and you are quite used to it and the readings you detect on your signal level and quality level, you can monitor the signal level bar graph and percentage. As you try different cable types and lengths, you can get a really good indication of what is happening on your cable by monitoring this reading. It not only tells you something about the RF signal, but it also adds in the DC current through the cable. If you were to use the same cable type, and just keep increasing the length, you can watch the signal level drop as the length increases. Similarly, if you keep the length of the cable constant, and change the cable type, you can compare the quality of each cable type against the others.
RADAR