If your build is heavy on discipline, yet you don't have little or no discipline generating skills, such as Preparation, Night Stalker, Perfectionist, etc, do you think Suppression Fire can do the job to support the heavy discipline usage?
If you use it strategically, only when there are big packs, I think you can certainly make up for not having Preparation.
The only downside of this may be that it'll not scale well with gears. You can only hit so many enemies in most cases, while Preparation will give you more and more discipline since your gears have more discipline as your gear gets better.
What do you think?