I know that possession spirits are limited by the max physical augmented attributes of a living host. I was just running a mission adventure and noticed that the insect spirits were well above these limits. Is the inhabitation spirit power limited in the same way as the possession power?

Based on the description in Street Magic, it looks like inhabitation actually transforms the host into a different creature type, whereas possession is more like a buff than anything (I guess?). Street Magic doesn't explicitly state the limitations either way that I can find, but since the inhabitation merge effectively isn't metahuman anymore, I don't see any reason it wouldn't be calculated the same way any other spirit attributes are (via Force +X).

If it's the Season 4 mission I think it is, yeah, the numbers are off for many of the Physical attributes compared to the Street Magic rules. I'm not sure why, unless I've completely missed something in how I'm calculating them.

Thanks, think I figured out where I went wrong in conversations with players. Why would they provide the stats for upgrading attributes i.e. attribute + "some value" if they were meant to work like possession spirits.

Thank you for the quick response.

My take on it is that the host is a vessel and should therefore follow the rules for such (pg. 150 SM & pg. 86 SM). A living vessel is limited in the boost it can have by its natural attributes. So an Insect spirit inhabiting a human would max its physical traits at 9. This should probably only hold for the Flesh form and Hybrids. The True form should act more like materialized spirits and get the bonuses listed in the spirit stat blocks for insect spirits.
So a force 6 soldier insect inhabiting an average human (stats of 3) and creating a flesh form or hybrid would max out all the physical stats to 9. As a true form the same spirit would follow the soldier stat block and have the following: B:8, A:6, R:7, S:9 (pg. 152 SM).
I think I would treat the Flesh form and Hybrid as a possession type for stats and movement and such and as a materialized type for the True form. After all, some of these spirit types can fly (wasp, fly, etc) but it makes no sense that a flesh form or hybrid can fly without wings. After all, fire spirits can fly but a person possessed by a fire spirit can not. Though they possess the skill of flight, flight is a movement type, not a power so doesn't transfer to the host.

EDIT: Read your edit. They provide the Force + X in the stat blocks because True Forms act like Materialized spirits and need that info. The Flesh form and hybrids act more like possession type and don't follow that info. Same as a fire spirit in materialized form needs his stat boosts from his stat block but as a possession type just adds force to the host stats.

One way to run it, I suppose, would be that Flesh Forms are limited based on the maximums normal for the original creature, Hybrid Forms are more distinctly different and thus are not (because, hey, let's make them actually have a point and be more dangerous), and the rules are fairly clear on true forms.

As these things aren't player options, its largely a question of "what does the GM want".

The only problem with that is that it makes the hybrids more powerful physically than either type above a given force value. Of course, if that is what the GM is going for, I suppose it isn't a problem.

Which means there's a purpose to each. True Forms operate as Materialization spirits, Flesh Forms are infiltrators, and Hybrid Forms are the muscle.