This IW cable is an RG-316 type replacement cable, similar to several other offerings in the marketplace. The main difference between any of these high performance cables and corrugated coax is return loss performance. The 1.35:1 SWR max with two connectors means typical performance in the 20dB R.L. area and in my experience corrugated coax is not capable of that level of performance at any frequency above that at which the spacing of the corrugations becomes a significant repeating discontinuity. One other note, FSJ1-50 is not particularly flexible, all marketing aside; its bend radius is twice that of the IW 1151 cable and four times that of other readily available cables of this type. In many applications the tighter bend radius and ease of installation offered by RG-replacement type cables overwhelms the apparent insertion loss advantage. I use "apparent insertion loss advantage" because the advantage can be severely limited by the poor return loss of typical corrugated coax assemblies. I hope that clarifies the advantages of this type of cable over corrugated coax.

It's unclear to me from this article what the advantage of this cable actually is. Andrew FSJ1 (1/4" corrugated coax) has an insertion loss less than a 1/3 of that listed for this cable at 16GHZ. It's a larger diameter, to be sure, but loss is usually a really big deal in my experience.