I've got a maxed Suros and it's pretty good but just not my cup of tea. In comparison to the Epilogue it's completely the other end of the Auto Rifle tree. The Suros shoots like a laser when upgraded so is pretty easy to master and works at longer ranges. I've not got the Epilogue but from what others have said and from looking at the stats it appears to be a close range Auto Rifle, which for me would make it ideal for some Crucible maps and ordinarily not much else. However with its Void damage it should also be useful against Praetorians in the VoG and in high level strikes with Void Burn modifier.