"alpha4" is out, see announcement and download links on my blog:
http://bkhome.org/blog/?viewDetailed=02910
This is built from Debian Squeeze armel packages. Is it slower than Raspbian? Try it, find out for yourself!
Regarding it's "alpha" status, well, all the distros for the Raspberry Pi are alpha quality, some more so than others. With this pup though, you might find that everything that you want to do, works.
It depends, please do read the Release Notes so that you know where the issues are that still need work.