James,
In my hybridizing class I point to two Echeverias that I have potted on my patio as goals that should be achievable in semps. One of them is a huge silver and the other a very dark brown, verging on black. This year I have a silver one that even surpasses the Echevaria and I'm working on a black semp with several very close.
The variegated ones are more difficult to obtain because we need a sort of splish-plashed variegated plant to use as a maternal parent. Both New Rhumba and Brillante are chimeras with one white histogenic layer. They will give either green or white (lethal) seedlings not more variegated ones. I do look for mutations that have those splish-splash sectors and have sectrs on two plants in the garden but no bloom on those plants.
Until then, we have good examples in other succulents for what we can achieve in semps.
Kevin
