I have already worked through full week solely on Mac and Leopard platform with excellent results. The productivity in using Java is actually higher, thanks to faster machine and Spaces allowing to have opened few Firefox windows with Spring documentation, terminals for Ant builds, Tomcat, Eclipse and Spype/Adium to keep in touch. Spaces is about as good as having multiple monitors - the ability of switching between both with mouse and keyboard fits well in my working habits.
Speaking of Spaces - try this neat trick: press F8 and while in Space view, F9 for Expose. This will rearrange previously hidden windows and allow to click on the one you want. Another neat feature is possibility to tell application to show up in assigned space - use Preferences, Spaces and the '+' button for this.
First time ever on Mac I had to print something and that was really interesting experience. After selecting Add printing, I was subconsciously expecting the dialog box asking to enter printer location URL or IP address and mentally getting ready to search for printer driver somewhere on the Net. The reality was different. Right after Add printer, OS-X somehow discovered both printer on network and I was ready to go without anything else to do on the black-and white laser. The second one (Konica-Minolta) did not have driver provided by the OS - something to finish up next week. I guess I should find out more about this Bonjour thing responsible for the printer discovery magic :-).
Also the Office documents compatibility got tested - both with iWork 08 and NeoOffice. Most documents converted without any issues - both Excel 2003 and Excel 2007 were perfectly readable in Numbers (and looked much nicer). I have experienced conversion issues with large complex document containing pivot tables and charts. Numbers notified that pivot tables cannot be converted and showed only charts, whereas NeoOffice sort-of converted the pivot tables but completely destroyed the charts. It looks like that having XP in virtual machine will be necessary after all - for situations like this. I have already installed Fusion and experimentally proved that the VM's created on Linux are transferable to Windows and Mac: I was able to install XP into VM created under Linux, saved binary state, moved to Windows, booted it there in VMWare Player and after installing ATG suite, the same VM was running with no issues at all in Fusion. Nice.
I have also mostly solved the synchronization issue of two subtrees. The open source application JFileSync does almost everything I need - except integrated visual file compare. I am also evaluating the Path Finder which has tabs and maybe most of the TotalCommander functionality I was missing - without doing the two windows approach. So far, looks very promising !