First of all we will release, together with this version, the packages updates. It means that you can install the beta now and run updates to reach the stable version, passing through all the other beta/rc stages of course. To get the updates you just have to register your email here: http://www.endian.com/community/register/ and then, in the command line, run `efw-upgrade`.
One of the big changes for this version is the architecture that has been modified to x86-64. Alpha1 architectures were 32bit i586 and 64bit core2duo. This last one requires cpu with ssse3 instructions that might be incompatible with some AMD cpus. This is the reason why we decided to use a more generic x86-64 bit architecture and just drop support for 32bit cpus. IMPORTANT: You can't upgrade from alpha1 to beta1 because of this architecture change. All alpha versions need to be re-installed with beta1 but you can always restore a backup.