You have to ensure you have all the latest Up2Dates for V4, backup config, Install V5, restore config, perform all Up2Dates, backup config, Install V6, restore config.
You have to ensure you have all the latest Up2Dates for V4, backup config, Install V5, restore config, perform all Up2Dates, backup config, Install V6, restore config.
I can't provide any reasons not to upgrade and in fact there may be many that would support it.
I don't run in a corporate environment... I only use ASL on my home ADSL line. V4.027 is meeting my needs very nicely but I was just curious as to your motivation to upgrade.
One issue that I am not sure has been resolved is the implementation of QoS. There have been numerous threads in the past about QoS in V5.x claiming that it did not function properly.