Wooshbuild V7 is the latest version and yes it can be put on the solo2
Install instructions are here.
http://www.techkings.org/threads/wooshbuild-v7.133480/
Just flash basebuild and follow the on screen instructions. Basebuild will ask if its ok to initalise your hdd so just select no, and your recordings will still be on your hdd ready to use as before.
In the link above you will also see a link to the wooshbuild support thread. This covers all boxes, so have a read before you start and you will probably find all you need to know
Openatv vs vix its all down to personal choice they both do the same thing really. Just flash woosbuild and make your own mind up if you dont like it then just go back to vix
I have a solo2 running wooshbuild and ive never had any trouble with it at all