I’d say three issues
- how to select a member who can be trusted when promoted as a moderator
Selecting people who can be bought off, or can defect, is selecting people who do not have the same goals as the admin. One way or another, you need enough contact and history with someone that you can confidently promote them. Obviously, that takes time, unless you happen to know them also in another context - whether another online or a real world context.
Even if category mods don’t have all the powers you might want, at least they have fewer powers than the ones you worry about. You can think of it as an intermediate level of promotion.
I might ask what kind of community it is: my community is probably average age in the 40s or 50s. If your community is average age under 20, I can see you might have more trouble with loyalty and maturity - at that age, most people still have a lot to learn, and friendships and loyalties can change a lot in a short time.