Chances are pretty high, that at least one new song of SoL will stay exclusively on SoL. Probably NO ONE ELSE BUT YOU. I actually think you can treat it as a single in that regard.
I've asked the same question over on JPC forums some days ago and pretty much everbody was sure those three new songs won't be on another album.
I guess if the content is it worth for you, go ahead. The price isn't that high and most people I saw are really happy about having so much PVs on BluRay in good quality.
But it seems PVs before 2009 aren't real HD?
http://tieba.baidu.com/p/3912796498