When is it better to employ a less experienced but more energetic & faster learning person than one with more experience & less motivation for change?

When there is more time to train, an energetic and a fast learner would be the best but when training time is less or absent, then an experienced resource would be a safe bet.

Your team has to have a balance between both experienced persones & enrgitic persons .

Energitic will give you qurantity which is required to deliver , but he has to be monitored experienced persons to  assure quality is there .

So i tink  1 Experienced with (2 Energitic   or3 max ) is a good balance

whenever it prompts to ....

When dimotivated experienced employees starts effecting negatively the business environment then its always the right time to substitute them with motivated employees who are eager to learn, show the right attitude and bring new fresh ideas.