Double curtain rod systems...

I've never seen these types of double curtain rod systems in the shops... but am just wondering what your thoughts are on them. Are they expensive? Do you think they are worth it? Or would you recommend buying all the components separatelly and going with a good quality and thick blockout curtain rod (at the front) and a less expensive one for the sheers (at the back)?

Would love to hear your thoughts, as always :)

B