I am also concerned about the system itself, because of what happened with the initial round of tickets... and thousands were available at that time! That said, only those of us with tickets can even log in or access the system, and only a percentage of those people will be trying to do the upgrade. So, the congestion SHOULD be less, but... the issues with upgrading tickets will definitely be present.
I'm assuming more than 250 people will try to upgrade, so it's a rush to the finish line which will surely result in some people being unhappy. It is kind of frustrating that many people who want these exclusive tickets will be left out, but I find it hard to complain when I know there are a lot of people who wanted to go to the festival in the first place yet couldn't secure tickets because of the system... so we should consider ourselves lucky.
Yes, if you spend a lot of money on merchandise, and actually get that free drink (if you were intending to drink anyway), it could be worth the money. Having exclusive seats and signing sessions would also be worth it, to some people. I thought about this and figured... I might as well try to get the upgrade, and if I don't, I won't be too upset about it. But, with all the issues with the system... I'm very cautious about possibly messing up my existing tickets.