Only war is focused around conflict and combat, your missions usually revolve around a conflict and your objectives are to help resolve the conflict.
I.e: Orks are raiding this planet
1st objective: Retake communication tower and send out distress signal
2nd objective: Recon missing battalion
3rd objective: ect
Dark heresy is about investigation, you are sent out to look into the dark corners and flush out any threats to the imperium. Investigation and Social skills are a bigger focus, where as your enemy won't be so blatantly obvious and ur missions more subtle.
I.E: There has been a murder of a retired Imperial Officer, he had made contact with the inquisition before he died seeking help.
Lead 1 his servants mention a Connection to an artifact dealer
Lead 2 the dealer remembers the officer brining him a strange artifact not long after some unknown woman came asking about it.
Lead 3 the woman is part of a cult and they think the artifact brings the dead back to life, or will grant them powers or what ever and now you must stop them.

Pointing out of 90 of the book the Psyker elite advance:
• Gains the Psyker trait, the Psyker aptitude, and a psy rating of 1.
You aren't totally gimped by going rogue Psyker mechanically.
You just have to pay a bit more for to catch up for
There is also the +10 to phenomenon, but you can push more though not recommended.
And you don't start with a focus so you Miss out on +10 (psyrating 2) and + 10 focus which believe me sucks untill u req it.
RP wise you have to have a bit of a radical group ;p good luck with that lol.
My group hasn't found out I am a unsactioned Psyker yet. It will be fun there is a SOB lols.

If you want players to fight you have to give them a reason to put their lives on the line.
Protecting an artifact
Fear of failing their Inquisitor
No escape or out of time
Most of the time it's, oh boy we found heresy better go tell someone else who can deal with it.
You have to pull them out of their scout mindset and put them into the its us or nothing mindset.

Keep in mind at the heart this is an investigation game, and as such combat is not the central aspect of the game.

A powerful sorcerer or heretek will have protections that make mere autoguns/Lasguns a joke. I think the standard adventure in the book ends up with a deamon that has 14t ... an auto gun or las gun has no chance of really threatening this thing.
 
The strength of these weapons lies in their ability to cause pining or crit fishing with full auto/semi auto. I would argue that while these weapons are in effective at ending a fight through pure dmg, but they can have a lasting impact on the overall fight. Forcing to keep enemies heads down while the party takes down a necessary target, picks them off one by one or achieves another important objective. On big bad bosses hopefully you packed some man stopper bullets or some other type of ammo for dealing with certain targets, and then you pepper them with it searching for that Righteous Fury, critical dmg can be a serious combat changer.
 
Autoguns and las guns have some of the best ammo upgrades in the game that can rival even the more deadly weapons.
* Peppering the Deamon with Holy Bullets
* Loading up Man Stopper Bullets for armored targets
Ect.

Keep in mind at the heart this is an investigation game, and as such combat is not the central aspect of the game.

A powerful sorcerer or heretek will have protections that make mere autoguns/Lasguns a joke. I think the standard adventure in the book ends up with a deamon that has 14t ... an auto gun or las gun has no chance of really threatening this thing.
 
The strength of these weapons lies in their ability to cause pining or crit fishing with full auto/semi auto. I would argue that while these weapons are in effective at ending a fight through pure dmg, but they can have a lasting impact on the overall fight. Forcing to keep enemies heads down while the party takes down a necessary target, picks them off one by one or achieves another important objective. On big bad bosses hopefully you packed some man stopper bullets or some other type of ammo for dealing with certain targets, and then you pepper them with it searching for that Righteous Fury, critical dmg can be a serious combat changer.
 
Autoguns and las guns have some of the best ammo upgrades in the game that can rival even the more deadly weapons.
* Peppering the Deamon with Holy Bullets
* Loading up Man Stopper Bullets for armored targets
Ect.

I think the opening adventure found in the core book has a good take on an dungeon crawl, if you keep up with the adventure it plays out like a chase scene. Your party dosnt have time to rest 24 hours unless they miss a certain important encounter here. And since there are several deadly battles in this adventure and it ends with an even more deadly battle it really lives up to the dungeon crawl. 

*Arrive Here search for clues
*Follow clues to Group X before they are silenced
*Group X brings you to Target Alpha 
*Target Alpha has information about "Main Plot to be carried out at this time"
*Will your players make it in time? Will they stop the forces of chaos? What will happen if they fail?

Did you take into your example of how soak works?
With auto/semi weapons having to deal with soak per hit.
Where as the sniper rifle can stack all its extra D10s onto one Hit.
 
That's a big difference that can add up. 
 
My question would be can you count on Autogun Crits enough to ignore the Sniper Rifles big single shot?
I mean 3d10 (One shot) vs 5d10(5 Shots) sounds scary until you start subtracting Cover/Armor/Toughness per shot.
 

I for one am a fan of a power mace or shock mace in a twf PC. Force them toughness checks to benefit from +20 tohit vs a stunned target. Then you can benefit from balanced sword for parrying/Pen/Dmg ect.