What's been the biggest benefit for you?
The benefits are so huge that they are hard to enumerate, so I'll pick the top 3 or 4. For the Lacuna Expanse, the main benefit was ease of development. There were no longer any hoops to jump through (the mod_perl landscape can be tricky to navigate). Sometime later Starman came out and that gave me an instant boost to performance, which was also nice. For WebGUI the middleware components were instrumental. They allowed us to eliminate a lot of code we previously had to write ourselves rather than using shared libraries. In addition, just switching from mod_perl 2 to Starman (no other changes), gave us a 300% performance boost.
You seem to be comfortable using a lot of new technologies with a reasonable amount of traffic. How do you see the risks and the rewards?
First and foremost Miyagawa, who wrote Starman and much of Plack, is my personal Perl hero. It seems like everything he writes is absolute gold. So the fact that he wrote it adds some confidence.
Awesome post on how the Lacuna Expanse uses Perl, and good plugs on Plack here and there :)