I am inclined to disagree.
I actually own the thing (hell you may own it too), but the ST8 AP3 barrage shot lacks predictability. Now if we are talking about a huge blob of enemies where you can never miss, that's cool, but generally speaking it's not a reliable enemy stomper. The 7 Inch D is ALWAYS handy depending on the enemy. Especially Necron Deathstars and Canoptic wraithstars.
However, if you are facing an enemy with NO Superheavies, with a hoard of low AS units, I can see how this will be plenty useful. If your concern is ignores cover... why don't you have markerlight support? It's not like Ignores Cover is hard to come by in our army.
A good example would be an Orc Mob. Drop the center of the blast on their big vehicles that are surrounded by a large number of scrubs. If it's OT, you have a +3 to blow it to bits from the 10/1 center ordnance shot. Everything around it takes a 7/4 (usually enough to kill hardboys dead) and the 5/5 for the scrubs. EVERYTHING THAT TAKES A WOUND MUST MAKE AN INITIATIVE TEST. If they fail, BS1/WS1 for the next round. This screws just about everything over if it's not eldar.
Don't forget you have your handy arm weapons to boot, usually enough to kill anything smaller then you. After thinking about it...yeah I consider these a worthy weapon.