I've been considering trying L4 before buying the package upgrade (which I'll probably do). I can't find a download page to get the new engine though.
http://downloads.logos.com/LBS4/LDLS4Installer/Logos4Setup.exe
BTW, some Logos 4 features don't work without the new resources found in the upgrades. See here:
http://www.logos.com/minimalcrossgrade
Randy, while you're downloading, please read the wiki and the FAQ.