Bear with me on this one, there's critique
I have done all the bosses except last one in Nefarian's Revenge, and I have done the 2 first bosses in Icewing Cavern, and the 2 first in Shadows of the Scourge, and sorry, but most of them are tank and spank.
I have in fact done all the bosses in Nefarian's Revenge except the 2 last ones, with only 2 persons. This included having to do some tricks on some of the bosses, but overall it was pretty much just hitting the boss until it died, and healing was not a problem. If you can do that in 2-man, you can do it in 5-man. You need to figure out ways to make the player have to do something out of the ordinary, like for example on the first boss in Shadows of the Scourge, you have to kill the boxes instead of the boss.
Sadly, yes
I'd love to have more boss maps, in fact, I'm working on two myself, but I am a beginner at mapmaking and I doubt they'll be great, even if I've managed to get someone who is very good at making bossfights to join one of the projects.
You're one of the few people who make boss maps that are decent though, even though there's some rough edges, your bosses have good potential, what I think is lacking is making them need human interaction, and maybe some tuning on abilities, so that they're not over- or underpowered.
One thing I ask though, if you do decide to continue Wc3 RPG, and decide to go back to the old heroes, please implement the tanking system you implemented for warriors (I haven't tested tanking with any other class) in this one, it really helped to not rely on a 10 second cooldown AoE taunt