Roundup of OSS cluster stacks: please let me know what you use

I am looking at new cluster stacks for a number of reasons. We have one internally (Tiburon) which is quite flexible and powerful, but I don’t want to push it out just yet (have some additional bits to deal with). I’d like to hear what people are using out there. Ones I am not interested in are Rocks and derivatives, Oscar. I am interested in xCAT2, and any others out there as stacks. Basically we want to see good/bad about any/all of them.