Ridvan,
Glad you got a chance to see some of my seedlings! I do use some quick start during the growing season, but my soil is also hand-mixed. I use a 1inch layer of potting soil on the surface (as suggested in Kevin's book), but beneath it is a combination of 50% inorganic and 50% organic components. I use worm castings and charcoal which really give the plants a boost, the rest is steer manure, compost, clay, pine bark, fine gravel, landscaping sand, which help with aeration drainage and add some nutrients of their own. Charcoal added to soil (or "Biochar") has been proven to increase yeild in a controlled study on corn, it's my belief that it has a similar affect on Sempervivum as it is a clean, microbe free source of nutrients. I use compost, but very little, it is easy to over do it with compost and expose the plants to excessive amounts of the very plant eating microbes that could turn on a weak semp and cause rot.
Your plantings look very organized and healthy, a good palette for growth and observation. I look forward to seeing what you come up with.
-Sol