I've always loved the fantasy of huge spaceships with wide arsenals they can bring to bear, that move slowly but inexorably and possess unstoppable firepower. As such, with this Battlecruiser hero concept, I wanted to craft a hero who could both push the line of battle slowly forward while attacking multiple targets, and also adapt his kit depending on the situation he's in; speccing into spell power or attack damage, as well as high sustained healing or brief but high armor. However, to counterbalance his adaptability and reward more skilled play, I came up with his unique energy system, which I also feel adds to the WH40K-esque battleship fantasy of having to manage your reactors' power across multiple systems simultaneously by forcing you to pick and choose what abilities you want to spend your precious energy on in battle--I'm an especially big fan of the concept of overloading your weapons at the cost of proportional risk with his heroics, especially as a strong mechanic for rewarding good timing & skilled play.
That said, I have no attachment to DuGalle in particular; he was just the best character I could come up with to captain the battlecruiser. Mengsk might work well as another candidate for the character, but I'm not sure. It feels almost mandatory to have a nuclear missile somewhere in Mengsk's kit, maybe as a random 20 talent.
Initially, I was thinking of making him a ranged assassin, but by virtue of the fact that his trait & Q ability revolve around being in range of as many people as possible, he'd need the survivability of a bruiser. He could perhaps be a multiclass hero by choosing to put his strength in his turrets or in his Yamato cannon through his talents, but since Varian got taken out of the multiclass role it seems like the dev team might not want more multiclass heroes.
I'm still playing with the idea of using his Energy as an alternative to normal ability cooldowns. Unfortunately, seeing as this concept would make all of his abilities' costs affect each other, it's hard to figure whether or not this would work, realistically, without being able to actively test it. And I may or may not have gone overboard with Yamato-themed talents. I do by no means think that this talent tree is wholly balanced or wholly viable.
Also: Although I've heard from a few people that I've proposed this idea to that it would conflict with Raynor's Hyperion, I don't feel that this is the case, because Hyperion exists as a separate, much larger battlecruiser in SCII co-op mode. Also, they got Deathwing into the game, so I feel like they can make anything work.