I use both types from UK hooks. The X-tension I've had on a couple of reels for years now - just keep cutting back at the business end to expose fresher braid for knotting to leaders. The Blue Marlin has snapped off casting light lures a couple of times from one reel I have it on - don't know why - I've set the drag on another reel and it takes 2/3rds breaking stain, as it should.
Well, like I said - I've had 50lb X-tension braid on a boat reel for about 5 years now - never had a problem. Likewise, I have 20 and 30lb on two spinning reels for almost as long.
The problem I had with the Blue Marlin was that I have it on a casting multiplier, which doubles as a light boat rod and a lure casting rod. Three times now I've lost a small casting pirk 'cos of a snap-off. I don't know whether this a problem of the reel or what - maybe this braid has poor abrasion resistance. I put the same braid (37lb) on an Avet SX reel and set the drag with a 22 lb weight on the end of the line, so why it snaps off with a 10g lure, I don't know.......In any event, I see no advantage over the X-tension braid.