Heroic dungeons more difficult on this realm?

I played on Frostmourne S2 briefly before quitting. Got to 80, did some stuff to unlock heroics and after a few very miserable runs I ended up leaving the realm. I think all the enemies had double hit points compared to Icecrown realm and did more damage to tanks. With low dps and that double hp, Voilet Hold HC was impossible for our group which was my breaking point.

So I wonder, what's the best way to tackle this issue if I were to try again in S3? I am thinking about tanking the dungeons myself because last time the tanks were really underperforming but I'm also interested in playing a balance druid or hunter because they've got really good AoE & single target damage even with 187/200 blue gear.

I felt this aswell during my time on Frostmourne. I've tried to find any information about it but i found none. Is there increased difficulty in dungeons/raids on frostmourne? The news thread only indicated "will be tuned as before" and not explaining how it's tuned at all.

There's no increased difficulty for 5-man content. Everyone is just normal geared and cant zerg through mechanics.

For Violet Hold here's few tips to make a run more tolerable:
1. Use a crystal on wall to kill multiple mobs portal waves. Multiple mobs always come from portals on sides upstairs and from the middle at the area.
2. If you have used all crystals it's best to focus on Captains first. These mobs use Mortal Strike effect which will make healing you harder. Mark them with skull and stun them so they cant Mortal Strike you.
3. Save a defensive cd for multiple mob portal where more than 2 Captains spawn. Talk with your healer to make sure you dont both use your cds on same wave.

Yeah, it's a skill issue - ppl can't faceroll content with 6K+ GS and suddenly it all falls apart, lol. Tactics? CC? Dispells? What's that?

I remember ~10 years ago the HC dungeons had broken DMG/HP values which often made them harder, some trash pulls were a mess even with gered people. I could carry hard as a healer/tank.
Hunter can be a good too cause you can MD, kite, CC, interrupt, dispell magic/enrage.

Overall - roll a utility class if you wanna carry. Hunter, shammy, pala, even priest or druid - they can counter the low IQ of the average PuG.