I provided the Sonic Visualizer binary from their site a few versions ago and it was very unstable, simply clicking certain buttons on the GUI made it go poof. Varpa is correct that my ISO's are limited to 2Gb not by Remastersys (that limit is 4Gb) but by the apache servers my web hosting uses which make a file larger than 2Gb not appear visible although they are there. Other than that my hosting is very good to work with and 2Gb seems like a reasonable size limit that kind of makes me keep an eye on keeping things lean.
As far as KDE4, I don't test other DE's, the fact is that in order to make AV Linux what is is I have to occasionally make some deals with the devil (devil=Debian unstable) and those deals have a cost somewhere. It has always been my intention for AV Linux to be a functional unit unto itself and not a universal Debian spin-off. If you want something that open-ended than use Ubuntu or pure Debian because they are made for that (although Ubuntu is completely useless as a multimedia OS unless you know the KXStudio PPAs and dozen or so other obscure PPA's to add to actually get version of the applications that work... look at the Ardour and Kdenlive forums sometime...end of rant)
As far as Debian if you want to compare, download an ISO of pure Squeeze and check out the default versions of everything and hopefully what AV Linux is giving you is worth the few choice constraints it asks of you. Granted Debian Testing and Sid solve some of those issues but can't be Remastered and Sid especially can pull the rug out from under you when you least expect it. I don't have to tell you Linux is about compromises, that is why there are thousands of distros and half a dozen of each kind of application...