Don't know the original poster's exact situation, but for example if you have a relatively small load of long-running transactions, random isn't good enough; if you happen to hit a busy system you really want to at least consider trying another system. (A real load-balancer is the brute force solution of course; one that understands the present load and can accurately predict the future load. But that's often beyond the budget of this kind of setup; and the commercial ones are optimized for large numbers of small transactions rather than the reverse.)