Not that I do speedruns myself much but I'm hearing so many complaints from those who do that trying to speedrun raids is far too dependant on critical healing.

For the best example check the fastest kill for regular kefka savage, where they abused healing from critical HP to generate three LB3s and an LB2 in under 5 minutes.

The general consensus is that it's taking all the fun out of it and perhaps a solution would be to just remove the bonus limit break from healing someone with very low HP.