Yes, a single QtSDK doesn't harm. But at least for Symbian I need to install the old one because at the new QtSDK is no Symbian target anymore. But for my MeeGo stuff I would like to use the new one with the newest QtCreater and I would say I need also the newest SDK later this year when Jolla arrives. At BlackBerry I have the Beta3 of the Native Cascades SDK but want to install the old stable native SDK too because I want to try some stuff on my Playbook which doesn't support Cascades. And I wan't to try in the future the newest QNX stuff in QtCreator which is currently in a early state. Mesing on a running machine is always a pain, at least for me.
So I thought I could get rid of all my problems by using VMs. Oh, I were so wrong...

As I wrote at twitter the N9 usb icon doesn't show up at the VM. Not even in the Massstorage mode. I don't know why, the BlackBerry is there but I'm unable to reconnect it to the VM since the host is blocking it instantly. I messed already more than 2 hours with the driver (deactivating, uninstalling ...) before writing this post. Nothing worked, if it is uninstalled windows is blocking it because it is searching for drivers.

So I guess the only finally working and best solution for every dev device I have here would be to make the different subnets visible to all devices in my network. Don't know why, google delivered so far only very confusing stuff... but I guess this is doable.