Hello, I would like your opinion on this. I to have a question about which coax I should be using.

I have the LAA++ about 4 feet off the ground and I have a 35 foot run of RG6 quad shield coax running from the LAA++ to the bias-t (which has BNC male to F female adapters on both ends) and then I've got a short 3 foot run of RG-58 (BNC Male) that connects to Ant C on my RSPdx.
The guy at the store told me that if I want to improve my antenna, I should ditch the RG-6 and loose the adapters as they will degrade the signal, but on the other hand, people are telling me that they use RG-6 quad shield coax because of the extra shielding that helps them keep out local RFI. So, I'm confused. Do I keep the RG-6 and adapters or should I find something like RG-213 or RG-8X and put a BNC connector on that? I really don't know what to do as I am getting tons of different answers. 
What are you guys using for the coax? My intention was to only use the LAA++ for 0-30 MHz but it totally kicks butt at 87 - 108 MHz, and the air band. In fact it's the best directional antenna I've ever had for FM radio.