RustIndy has it right.
If you do not care at all about your current layout (and I do mean at all), then go for it, and start over.
If though, you quite like your layout, then that guide to which you refer will break it.
I wrote the new guide, and the post here, and on Codex because as 1.5 gets closer, more people here may be tempted to upgrade, and what I and the other forum supporters do not need is dozens of people posting saying "1.5 broke my blog".
It won't break your blog if you do it right, or, do as many people have here - install a testblog and play there until release.