I have been raising a Hero as a second main after reaching 250 on my main. He's currently 23x and can solo everything up to Lotus. He's extremely strong, and Worldreaver is absolutely broken in that it's pretty much pure final damage gain due to the attack speed cap in GMS and because of the frequent access to i-frames. However, I don't really understand why they are considered such good bossers. Perhaps in bosses like Lotus, where you are able to hit the boss most of the time, classes with consistent damage are able to clear relatively quickly. 

However, I do not understand how they'd be great even in bosses such as Damien, where burst is much more valued than consistency. If I'm correct, one of the fastest Reboot Damien solos on Yt is by a Hero, and the entire comments section is a debate between the player being a great player and Heroes just being busted in GMS. I think it's a bit of both, but I would have imagined that there would be a fair number of classes that can quite easily surpass Heroes in such a bossing setting. With that said I'm quite happy with how Hero has been so far; this was just something I had on mind for a while.

What I am going to say could be pretty far-fetched and possibly misinformed, but I think this is because Heroes just have broken damage output in general. Whether or not your class is burst-oriented doesn't matter so much if your consistent damage is close in terms of output to other classes' bursts. This is in tandem with the argument as to why a Thunder Breaker was in one of the first Hard Lucid clears in GMS.

Along with Hero's great funding efficiency due to having the largest amount of FD% in the game, I personally think the matter comes down to the fact that Heroes have consistent, but extremely strong consistent damage. Also, I imagine their burst damage wouldn't be that bad if you stack Cry Valhalla with Burning Soul Blade + Worldreaver. It is very important to take the time to level up at the beginning of the game. Whenever you need to buy Maplestory mesos, you can turn to ms4mesos.com for help. We has cheap Ms mesos.