I don't think this is a configurable option in Unity, but you can edit the source code to change the duration. If you've not downloaded source and compiled your own packages before, you can do so as follows. From your home directory in a terminal window:
apt-get source unity
cd unity-<version number>
Look for the line which says:
Launcher.cpp:const int Launcher::Launcher::ANIM_DURATION_SHORT = 125;
and maybe double the duration. If you've never built a package from source before you're going to need a few tools. So do:
sudo apt-get install build-essential devscripts
Then to get the dependencies neccessary for unity to build properly:
sudo apt-get build-dep unity
Finally create the package and install:
debuild -us -uc
sudo dpkg -i unity*.deb
If you're having problems with dependencies let me know, and I'll try to help you figure out what you're missing.
I'm not sure if there's a way to flag the skip_delay argument either. You may want to file a bug report with the Unity team to see if you can get them to allow this variable to be customized. Otherwise you may have to patch and compile Unity yourself.