Currently, I am still debating between Ubuntu (9.04 or 8.04 LTS) and openSuSE (11.1 or 11.2), for a LTSP server. My main concern is that while Ubuntu is a lot better if one use CLI all the time, openSuSE have more propriety drivers and stuff.

So I think the question is:
a) For server, how are their performance?
b) Easy-LTSP vs LTSP-Manager

If it's a webserver I would go with Ubuntu, due to its simplicity. However, for LTSP, aside from performance wise on the sever (and thus I will likely provide xfce as desktop interface), I also want it to be of easy to use for the students. I heard that in the next release, openSuSE will have an education package, as well as having a LTSP properly setted up and a more official GUI management tool.

And the first sign of eliteness from one of the distribution camp will likely make me jump to the other one. That is my greastest gripe with many of my fellow linux users.

I am not sure whether this an answer to your question, but I'll give you my point of view, in case it helps.

My opinion is that really isn't much of an underlying performance difference between distros in normal usage. One difference is how distros view defaults, and how much crud (sorry to be technical) gets installed and run by default, but, if you equalised those factors, the performance would be pretty similar - only separable by benchmarking, not casual observation.

Of course, if you were to try to equalise those features, you would have to know what you were doing and that is beyond the skill available to the newbies who are the target of some of the 'made simple' distros.

Personally, I like SuSE, but that's primarily because I like kde, and there isn't a big choice of distros that do a good job with kde. OTOH, .deb and attendant utilities would be my slight preference, if I had a free choice (SuSEs handling of multiple repos has improved with 11.1, but is probably still behind what you get with .debs).

And also, I like distros with big repos, and while you can everything in a debian repo (I'd like to think that I like a lean stripped down machine, but you should see how much gets installled after a few months!), if you are going to get everything from debian, why not use debian?

OTOH, its easier with SuSE to get control at install time over what goes onto your system, because the install selection is more finely grained. On gthe other other hand, you can always delete stuff (if you know what you can delete).

And then there is community; the *buntu community is bigger and livelier, but how much of that is other people who are in the same situation as you and how much can actually help you.

The more i look into LTSP, the more I realized that, while Ubuntu will be more integrated with LTSP, openSuSE's LTSP will be far easier to manage.

As I research LTSP, this is what i can gather:
-Ubuntu/debian have better integration of LTSP-5, if not the best
-openSuSE, though late in this game (and is still in development), is able to provide a better GUI setup.

Of course,I also find LTSP's tool for each distribution:

In SuSE, you have Easy-LTSP
In ubuntu, you use Thin client Manager + Sabayon.

So did I got it right?