To make str tank work you need both a good tank and a good healer. If you notice that the healer isn't good enough or if they ask, you should switch to vit. I have both a vit set and a str set.

If I'm running dungeons I'll use vit for big pulls and str for bosses. I also think that str tank is better at teaching tanks and healers on when to use defensive cooldowns and heals.

I have been running ex susano and lakshmi as a str tank with no problems except when the healers as slow on shields and heals. My fc/raid friend said he likes healing me more because it let's him use Excogitation more often.