After having plenty of good custom rods built and buying enough off-the-rack rods to fill the all the joist hooks on my basement ceiling, I fail to see the big advantage to using a Loomis rod or blank in a salt water application. Their saltwater series of blanks are either all basic standard modulus graphite or composite glass/graphite, no different than most other manufacturers, just more money.
In a fresh-water application there are more pronounced differences, with some of the ultra-high modulus proprietary graphites Loomis uses having an apparent advantage and a significant following, based on what I read on the FW Bass fishing boards. But even there, there are plenty of really quality competitive blanks being built these days. So "GLX" is Loomis' top of the line $300 blank. St. Croix has an "SC-V" that they use in their "Expert" line that is every bit as light, sensitive and FRAGILE. And less money.
Throw in the fact that Loomis wants $50 to replace a broken rod and frankly I fail to see any advantage to using their product at the excessive prices they charge. For what you pay up front, they already got paid for the replacement, IMO. They make quite a big deal about the replacement for $50. At what they charge it ought to be free. I know from personal experience that St. Croix does the right thing and for me they replaced a rod that was clearly not broken due to any possible fault of theirs, unless they manufacture Chevy Van Doors too. Of all of them, I'd go with the St. Croix first, then something in a Seeker or Calstar. If you want something more, look for a custom weapon built on a Cape Fear blank. I have two and they are absolutely awesome. Best I know of.