Does Songscribler gain any rights to your music?
If you decide to quit them, have they any hold over you?
They indicate that their percentage is 20% (I think). Any other fees? Collateral charges?
How will they advertise?
Do they have a nest egg to get them through the initial organization and set-up?
Do they have their own recording equipment-studio, or will this be subcontracted? Or is the musician-subscriber expected to furnish a cd?

Will the website be professionally set-up?

I believe some Mudcatters, like INOBU, have done their own cds or are in a cooperative. PM him and others. Would that be a better way to go?

Without knowing what kind of operation this outfit will set up, it is hard for anyone to give advice.