I am completely aware that Dark Heresy is not supposed to be exactly like the 40k miniature game. The themes and ideal mechanics of a role-playing game is not similar to a miniature war game. Likewise, the setting details does not have to be completely identical. A shooting fase in the wargame could present several rounds of combat in the RPG, and a "dead" model in the wargame may just be severely wounded or unconscious. However, I think it is a problem when the mechanics used in Dark Heresy to model the signature weapons of the setting causes the weapons and armors to be barely recogniceable. For instance:
Bolter: this is an armor-piercing micro-missile launcher. It has a 67% chance of killing or disanling a veteran imperial guard soldier in the wargame. It easily dispatches orks, and even have a 17% chance of killing a fully armored space marine. In DH it needs 4-6 hits to be able to kill the same imperial guard, if he is unarmored (disregarding an extremely unlikely streak of critical hits).
Plasma gun: this weapon fires superheated plasma capeable of destroying tanks and APCs. It kills space marines with frightening ease (83% chance). The weapon becomes so hot that it can kill or disable a space marine who fires it (33% chance if it overheats). In DH it is unlikely to kill an unarmored man with 3 hits.
Meltagun: this weapon is practically able to destroy anything. It kills space marines as easily as a plasma gun, is almost incapeable of not severely damaging a dreadnought that is hit by it, and is even quite capeable of damaging and eventually destroying an enourmous titan weighing millions of kilos. In DH it is unlikely to kill an unarmored man with 2 hits.
Power armor: this armor is capeable of stopping the main cannon of a tank more often than not 67%). It reliably protects against heavy bolters, heavy flamers, and alot of other heavy weapons. In DH it barely increases survivability against anything but the least damaging weapons. In the majority of cases an armor does not do much to increase survivability if it does not completely prevent a wound. It is a great way to prevent damage from auto-pistols, however.
I think this disparity is a major problem. It seems silly that all these tank-killing super weapons may have less stopping power than a 9mm pistol would have in real life. It ruins suspension of disbelief, and makes the combat system unbelieveable.