3.0.1 or 4.0 for a fresh server-type install

[John Cochrane]

Dear YDL users....

I've decided to risk a potentially more savage mauling from the 'big
boys'n'girls', and ask this question in the general ML.

I'm ready to start downloading a set of ISOs for a fresh/newbie YDL install,
but just before I hit the 'go' button, I had an uncomfortable doubt about
whether I should be getting hold of 3.0.1 or 4.0

As ever in the world of software, newer is not always better, or the most
appropriate!

A little more information.....

The task at hand: the most important primary goal for this install is to
initially experiment and eventually (hopefully soon) succeed in setting up a
comprehensive e-mail server, on which I plan to:

(i) switch over the useful correspondence from several other 'normal' e-mail
addresses to a set of new 'user-controlled' e-mail addresses, thereby
jettisoning the all the junk contacts accumulated over years!

(ii) develop the e-mail server to support all aspects of e-mail activity
that I require within my (self-employed) work.

Although initially I can afford to make mistakes and start over in order to
arrive at my goal, ultimately, this has to be a secure and reliable working
box.

The hardware: possibilities within a five machine group.

Machines 1&2: The initial obvious candidates are a pair of identical Beige
G3s, with the attractive benefit of being able to stagger progress during
install and setup (providing a fallback) and ultimately, to end up with a
primary and an identical backup box. However, being 'Old World' I suppose
they lend themselves more directly to YDL 3.0.1, although if I am correct, a
YDL 4.0 install is possible, though not supported.

Machine 3: A single B&W G3.

Machines 4&5: A Pair of identical G4/400AGPs. Benefits of a pair as above.
Availability not definite but can be brought about if highly preferable.

And so to the burning question: for the task at hand, and given the hardware
options, would the experienced amongst you set about this task using the
more established (and possibly error-free) YDL3.0.1, or push ahead with the
newer (but possibly less stable?) YDL4.0

This seems to be the most important decision to make first, and will
determine the entire install experience, reliability and security over the
coming months.

Thanks to all in advance.

John