I haven't used salaries. The only thing to remember is that treasure scales very very quickly.
With XP, +4 levels leads to x2 XP.
With magic items, and hence with treasure parcels, +5 levels leads to x5 XP.
This means, for example, that if you design an encounter and place some treasure with it, the contribution that the treasure makes to an overall level's worth will drop off at a quicker rate than the contribution that the encounter makes to an overall level's worth of XP. This makes classic "status quo" encounter design a bit tricky, and probably has implications you need to think through for the salary idea.
Putting it another way: a salary that is meaningful at 1st level will be getting close to unmeaningful 4 levels later, when the treasures are all 5 times more valuable.