Strength and Power Endurance are generally what we require to climb at or close to our limit. Whilst strength endurance is for climbing up to around 70-80% of our top effort, Power Endurance is more 80% and above. Both result in lactate accumulation and getting pumped. Whilst some of the training is about understanding how far you can go into the red once you get pumped, it is also about developing the our tolerance to lactate.
Which one to focus on depends on the routes you are wanting to climb. With power endurance often suited to short hard routes and longer boulder problems. Whilst Strength Endurance will help with long and sustained routes that are over 20 moves long.
In general if we are periodising our training programs then Strength and Power Endurance are among the last things we train. It is also important not to focus on this area for extended periods, as we induce high levels of lactate accumulation in our muscles. If we continue to do this for an extended period then like anything constantly soaked in acid, our muscles and strength will slowly be eroded away.