I double checked the wiki and you're right, Rogues get Expertise at both level 1 and level 6 and each expertise is given to two different skill proficiencies for a total of expertise in four skill proficiencies.
"Expertise is a passive feature that allows a character to double their Proficiency bonus on a skill. When a character gains this feature, they may choose two Skills they are Proficient in and gain Expertise in both of those Skills."
Having said that, I'm also right in that Expertise is also earned by Bards at both level 3 and level 10 so just like Rogues, Bards end up having the same number of expertise in 4 total skill proficiencies plus the additional 2 skill proficiencies that they get over any Rogue if a Lore Bard.
In regards to "Rogues being about high single target damage, so they're basically boss slayers", I would think that the Gloomstalker Rangers fills that niche better than any Rogue and would even say that a Gloomstalker Ranger is more viable playing a solo Dark Urge than any Rogue.
You're totally right about Bards being support/utility oriented though which to mind way of thinking, makes them a more appropriate class for a companion than for a MC, which is the main reason of my reluctance to play a MC as a Bard and I get the feeling that you share that sentiment which is why you would prefer a Rogue as opposed to a Bard for a MC.
There is a solid argument for the Gloomstalker Ranger and Lore bard but I like Rogue much better because it strikes probably the best balancee between hitting power and skill monkey. Being the face of the party is important because in important story moments and at camp you can't have a companion roll the skill or saving throws for you and I don't want my character to be the support role because I want Shadowheart in the party. On top of all that specifically for the Dark Urge the connection to Bhaal and knowing the first of the Dark Urge specific rewards makes it clear to me we're going down the Rogue Assassin gear path...Bhaal himself in life was a shapeshifter Rogue Assassin, and that's what Orin is too. So yeah, I'm not willing to give up skill proficiencies for the Gloomstalker Ranger and not willing to give up combat effectiveness for the Lore Bard, and the Dark Urge connection to Bhaal and the rewards we get from that origin makes the Rogue Assassin a no-brainer for me.
