I'm running 1.21, and my uptime has on occasion been for days or even weeks. I'm still not happy with the router or firmware and will be replacing it with a non-dlink router tonight.
Uptime doesn't mean performance. It would be pathetically easy for me to keep my router running for days, but I assure you the bits I've pushed through would be minimal at best, without high burst activity.
Any time I've pushed the router it would lock up. Considering the main reason as to why I got the router was due to its performance metrics when compared to other routers puts me in an untenable position. What's sad is I have most of the features disabled on the router. I don't enable wireless or DNS (much less advanced DNS). I can easily lock the router up by doing large scale file copies from one machine to another on 100Mb. The router is is gigE rated and it can't handle 100Mb. Simply playing a movie on my ps3 via media share stresses the router to the point where I can't be doing anything else at the same time. I can get around this via restricting my network related activities, but why should I?