Ask HN: Lift and building realtime webapps

I'd appreciate it if anyone could share any experiences, positive or negative with the Lift web framework. Our development team is familiar with Java and related technologies and we're looking at platforms for a greenfields project that will allow us to build realtime messaging services (in this case for medical referrals). We were attracted to Lift as it has excellent support for Comet, supposedly allows for very secure apps, and runs on the jvm (nice, but not a requirement).

My only initial concern is that without any prior experience with Scala we might find some of the concepts in Lift too foreign. Are there other approaches to building realtime systems that you'd recommend as an alternative or are we on the right track?