I thought that they were people who had committed crimes for the most part and were put to work in gladiatorial arenas for the entertainment of others with a countdown timer that explodes their hearts otherwise.
But they were still people, not servitors. I liked the thought of a gladiator being 'rescued' by an Inquisitor, with his clock stopped at a relatively low time limit, that way if he ever fails or displeases the man in some way, bye bye. If used as a background package, he'd have uses of implant weapons (ranged and melee) and something like melee weapon training (chain) as starting traits, along with some sort of bionic replacement.
If used as an alternative career rank, could be an interesting one for Guardsmen, Assassins, and Scum alike, increasing their combat proficiencies, granting access to various implant weapons like the Maltek stalker, etc, etc. but would require a Techpriest to perform all the upgrades, and the clock could be something that's optional based on the GM's discretion or something.
I think it's a possibility, but one that is similar in style to that of a Maltek Stalker, only instead of an assassin with a bit of discretion, he's a drugged out raging psycho with all the discretion of an atom bomb.