I am using Cat5 with Corrosion X. This year my display was almost always wet via rain or snow and the days that had no precipitation we had sub 0 degrees F. I did have 3 connections that I had to replace that were on the ground (grass) under my mega tree. On my roof I have 3 30'+ Cat 5 runs with no issues.
My long runs are as follows SS Active Hub>Cat 5 long run>SSC>Cat 5 under 3' to SSs.
My megatree was 16' tall. i had a 3/4" metal emt pipe that i bent into a half circle and suspended it 2' off the ground. I attached my SSC's to that via a bungee cord. I had no issues. I did not use Corrosion X any place.
I made sure that my cat5 connections were facing down. If water came it would not pool in the connector. Or at least i thought i did. I did have one failure with melting snow that filled a cat5 connector on my roofline. It blew a fuse. try to make the cat 5 connections face down.
You also asked the cost, the 3 pin connectors were $0.50 each.
i like the cat5 connector. i soldered 3 pin connector to the ends of all my strings and flex strips. i soldered some between my arches. I have shrink tubing on the wirews and then shrink tubing over the entire thinbg, like 3 to 4" of it. i had zero issues with the 3 pin waterproof connectors. my only issues was it gets to be time to solder snd shrink sleeve the connections.
I had 20x120 flex strips, 16x128 strings. I kept the ssc's off the ground and tried to point the cat 5 facing down.
my vote would be to keep the cat5.
thanks