Demo site up for sale

And in what way does that impact on the plugin’s effectivity?

Not sure, if I can’t see a demo. Sorry, but as a potential client I would like to see how it works especially since you have a link to a demo site. Unfortunately it doesn’t fill me with confidence, I will however give you 10 out of 10 for replying to a bit of constructive criticism. If you are as quick with your support as you were in your reply to my posting I would say that the plugin might be worth trying as support is an essential part of the jigsaw.