I can’t speak to the effectivity in dungeons, but I intend on a similar plan for my first team: 5 warlocks to aid the simplicity. The mixed composition certainly adds fun complexity though.

You would lose a tank pet, but if soloing dungeons is a huge goal, adding a healer might be worthwhile. Adds another set of buffs as well

Clearly the most slam dunk solution is tank+ healer+ 3 dps. The single melee character won’t slow you down as much if you intend to loot, as you’ll still have to run to every single body