Is there a rational reason to wait for the release date to download, install or update to the next version of Ubuntu?

If you require a super-stable working environment, I'd recommend waiting until the first Stable Release Updates (SRUs) are available. This usually happens within a few days of the official release. As the non-LTS releases tend to have more progressive enhancements and new features, they can contain bugs that have sneaked past the initial testing.

Also, waiting for the official release gives a chance to enjoy the growing excitement and buzz within the community (if you use irc, Twitter or identi.ca you'll know what I mean) :)

If you use a computer for work, any bug may still affect you (either seriously, or just make you lose some time), so you might want to take a conservative approach and upgrade when the new release has been officially released and the first "new release bugs" have been ironed out.

On the other hand, if you have time and skill on your hands, you are very much welcome to install the pre-release Ubuntu and help the developers by reporting any bugs you find.

In the end, I guess it just boils down to how much time you can spend on the new shiny Ubuntu :-)

My name is msw and I'm an upgrade junkie.

Okay, now that that's out of the way, for the installations that I have made on friends' machines who "just want stuff to work", there is no reason at all to ever leave Lucid "Long Term Support". They don't care about the changes that will mostly be invisible to them and they keep updating as update-manager instructs so I consider them "current". I've also replaced the Lucid "pig vomit" boot-screen/default background, so the most glaring defect of Lucid is already gone ;)

For vanilla machines like mine, I've found a single defect since Beta 1, and it was fixed the day after I reported it (not because of my report, it had already been uncovered). Helping to defray the network load on M-Day is a pretty good reason. It is unfortunate that dist-upgrade doesn't handle torrents - or even to take an idea from Blizzard - start torrenting the majority of the bits around a week in advance at low priority.

On the other hand, since the granularity of a Debian/Ubuntu upgrade is a package, even a single byte change induces one or more package upgrades; dist-upgrade is bandwidth and storage heavy and to preload for those who don't know what a Meerkat is would be wasteful.

The best reason to install the release version is simply that that's what everyone else is doing.

There is value in being in the same boat as a large number of other people. Problems you have are likely to be experienced by other people, which increases the likelihood you'll be able to help each other and find a fix. This is one of the main advantages Ubuntu has over other distros today.

OK, there's not going to be much of a real difference between a fresh release-version Maverick and one that was installed from Beta and upgraded to Release. But you'll always been slightly unsure. A year down the line when you try to do a dist-upgrade and the dependencies get wedged, did that happen because you chose a combination of packages or installed a driver during the Beta phase that then got in a weird state when Release updated them? Do you have a strange bunch of settings no-one else does because you installed before Release changed them? and so on.

I've been using 10.10 since it hit beta, as I do for most Ubuntu releases. With all the bells and whistles enabled (Compiz, Nvidia drivers, etc.) I've had virtually no trouble. The only problems I encountered were months ago and they were minor. Lucid was another story, but if you want 10.10 and are going to upgrade anyway (the home desktop version is the only one I can speak for) I say go for it!