So, I used Ufos Hero Editor to create a Cannon Dwarf level 40 quickly. Difficulty is Silver. Cannon Blast is only used as boss killer. I made a level 80 Cannon Blast combo. That would be 2 runes each level in theory. No problem and realistic. Desert Dragon goes down after two combos. No sets, uniques, or special gear were used. While I was fighting my way through the Goblin flats, I had a lot of fun with the Dwarf. Just as you. He is definitely the next on my list, as soon as I got enough of the Vampire.
I want to give Dwarven Armor a chance + Entrench. Combined with a high level Hard Hit combo it will surely work, but I need to find, or buy some special weapons first that cut through the Dragons defense. As MetaL said, you have to know the Dragons soft spot.
I agree that currently the amount of builds are a bit limited for a single character. I have difficulties to variate my Vampires since they depend on certain uniques. Rings, mostly. Currently I got two viable builds, the rest are either tiny variants, or not viable. But I believe as soon as sets get a rework and class related uniques too, the amount of possible builds will increase. Time and a lot of testing is necessary, who am I telling that, and it is of course a matter of motivation. Since I have cursed the game more than one time, I roughly understand how big reborn really is.
Tried Cannon Dwarf vs Ice Dragon. No problem.