The 30T GLR's typically leave a smoother ripped edge than a 24T FTG ripper, but aren't designed to operate efficiently in materials over 1" thick, so they're really not intended to replace your 24T ripper. As Tod stated, many 24T rippers leave a glueable edge. You can get glue ready edges from most decent 40 and 50T general purpose and combo blades too, and many of those will even rip thicker stock than the GLR's b/c they have a more aggressive hook, plus they yield a decent crosscut which the GLR's aren't known for. The GLR's do have the advantage of a durable triple chip grind so if you plan to rip alot of something like 1" hardwoods or MDF that needs a smooth edge, they're a great choice.
So they do work as advertised, but they are a task specific blade and aren't a necessity if you've already got a good general purp blade. Anyone know of any advantages I missed?