Righto - Been playing about and honestly think that this class is completely viable as a support class, buffing allies and making them more powerful. See what you think, let me know what you have tried!
If you run with a Crusader with Heavy Flamer you can Gib with Constrict at will. Does inferno pistol have high Suppression? hrm...if so then there may be a hybrid..
Bio Lightning with Vulnerability Mastery and +50% suppression damage Mastery.
Signums with Supression damage.
Precognitive dodge with All Damage Mastery.
For Eg if you can make a crusader capable of front lining enemies that would normally kill him. Or if you can stop the assassin dieing in 1 hit at +400 difficulty. Then your job is done. Admittedly this only really applies to higher difficulties but it goes without saying that at lower levels having 4 dps classes is usually most efficient.