There are still some crash reports for LuaTeX on i386-linux, so you might want to wait for them to be resolved first. Also, there is (almost) no functional change between TeX Live 2011 and 2012, more or less only a few minor math-related patches by Khaled. LuaTeX trunk might contain further changes though, but ConTeXt is still perfectly happy with last year's LuaTeX (which has never been the case earlier), so there is no big rush. Mojca