I am currently doing the 24 week plan.
You end up stabilising at about 10 hours a week in the base. A little less toward the end of the plan but the sessions are more intense. These numbers include 1-3 hours a week of strength training.
I add climbing on top of the plan. Also worth bearing in mind a lot of the uphill workout only include uphill time, so if you need to hike down from your hill that will add some hours of easy on top.
I think its a great plan. I thought I was doing more volume, but actually I was doing peaks and troughs. When you do 10 hours in a week and its day in day out 90 min run, 2 hours run, 3 hour hike etc, the training effect adds up!