About a reason to use older versions of EP, there may be cases of older simulated models that one wants only to have a look at it or at the results and sometimes it is better to run that model on the native version. This is partly because errors on migration from some versions to others are painfull and not complete, partly because this will save time.
There are also cases that the newer version avaiable has bugs that can be worse than the ones we already know from a previous version and some results can be doubtfull for not knowing what is happening with the software. This ocurred with version 7.0, that me and some colleagues have had trouble with the "setpoint not met" sumary on tables, wich sometimes appeared with strange data.
We did not look furder on this particular bug because the version 7.1 was released shortly after, but the bug made me suspecious enough to go back and use the EP 6 so that I could rely on my simulations results.
This said, I believe it is of great interest of EP users to have a place where we can get any of the previous versions and for all platforms, with some "generic" licence to make it easier to live with EP updates. I would prefer to have access to the source code, but the price is rather expensive (US$5.000?) for personal curiosity and it is not clear if I would have to buy it for each version.
This is only my opinion, and I do maintain a personal archive of older versions of EP, if anyone wants them please send me an email, but I would prefer that this old versions archive (not support, only software availability for friendly transitions and learning) came from the oficial sources.
I have the following versions available (mostly I go back to 4, 5 and 6):
for linux - V6.0, V7.0, V7.1
for windows - V2.0, V2.1, V2.2, V3.0, V3.1, V4.0, V5.0, V6.0, V7.0, V7.1
hope I can help,
Leandro M Biondo
Energy Consultant and Meteorologist
CTE - São Paulo - Brazil