This is a solid source of health soak if you've got poor in-class options for it and I think its best comparison is Bulletproof Vest (3). If you spend the same 3 XP on Armored Carapace and Dominance (to remove the ally slot) you've got the following differences:
- One less soak
- Two Summoned Servitors in your deck for the price of one Bulletproof Vest
ThreeIt occupies an Arcane slot instead of the Body slot- It can be assigned damage dealt to allies
Having an additional copy is a huge boon as the odds of both of them being buried in the bottom of your deck is a lot lower, and you can often have the other copy ready in hand when the first eats dirt. The biggest advantage occurs when you spend just one additional XP on Wings of Night since it will now repay its action cost, likely several times. This also puts it in the perfect XP cost for whoever has access to 0-2 .
The one issue is of course having an asset to discard. My Norman only had hands for one Magnifying Glass and his book in the other, but two glasses in the deck so that solved itself. For anyone else, I'd advise against rushing your servitor out. The perfect moment to play Summoned Servitor is mid-scenario when you've got a depleted assed ready to be sacrificed and know that you will move this turn.