Is it just me, or can you take task spirits in a possession-based tradition, add in some channeling metamagic, and then completely re-define what the term jack-of-all trades means?

Nope, it's not just you. On the other hand, materialzing spirits are much more fun if you bound a few.

'cept drain. Don't forget drain.

Drain heals, given the opportunity. My credstick balance after a shopping spree at World-O-Skillsofts, not so much.

but a spirit only last as long as the number of tasks. a skillsoft last as long as whatever its stored on

Also what about extended tests with a time interval long enough to prevent a spirit from performing it before dawn/sunset? You want to pay 500 per skill point to bind it, then only get <success> uses out of it? Skill softs aren't sounding so expensive after all?

Skillsofts have no drain.
Guns have no drain.

It is also another mark for the multiple spirit sustaining penalty optional rule.