Well id say to me i like them both, and Leopard is growing on me.
Coming from someone who runs 2 systems with Tiger as the main OS and has bootable copies of leopard for each machine. and one machine that runs Leopard primarily.
I opted to keep my Tiger installs on each machine as there is some software that seems to run alittle bit better under that platform, but not by much (mainly CS2 and Macromedia Studio etc); they all run fine under Leopard but alittle bit more solid under Tiger.
The whole Time Machine option, is great and useful.
The one machine I run Leopard solely on uses it as an incremental back up process; that way incase i happened to remove something or quite a bit of data or items ican snatch em up right away without cloning that system state.
With Tiger it was alot more trickier to do, aside from having to reimage from a clone or a backup.
I still clone my Leopard primary OS, but Time Machine helps me keep the marginal minimal files.
And to try it out to see how well Time Machine structured data, I did a complete reinstall off a blank drive of Leoprd and said to load from Time Machine and there I was, back and running from where i previously left off.
I say stick with what works for you, but try to do what you do in Tiger and match that with Leopard.
For me everything seems to be running much smoother under Leopard.
An old PowerMac G5 1.8 Single ihad that only contained OS 10.2.7 or something like that ran amazingly well with leopard installed.
Some of my favorite features are being able to file transfer between networked macs much more conveniently as my network has a few up and running most of the day i may need to get data to and from eachmachine and its been flawless so far.
Mightneed to give it some more time, its definitely a change and I still enjoy both OS' no doubt. but its definitely a great OS from my personal experience.
