The only time I have had the concurrency problem
with a licensed version of Oracle 8i was when we were
using the connection  Manager to pass the connection
through a firewall. Unbeknown to us, client had set up
the max number of concurrent  connections to 8 in the
configuration. They swore the problem  was our code; and we
debugged this for three weeks. I checked out the OTN
(Oracle Technology Network) and low and behold they
described the problem and the solution. The client
was a little red-faced; and a little put out at
having to pay for the hours of debugging that THEY had
caused. I did check and the Personal edition limits the
number of current connections, also. But, that's why the
call it the Personal edition... it's for developers to
test with. Letting developers download it is a great
way for them to get to know Oracle (IBM does this
with DB2/UDB, also). If developers learn a DB, then
they are likely to recommend it to clients (because
they are familiar with it). Most developers are not
aquainted with the license costs...