I just finished my first three-day-in-a-row training for quite some time. Seems like I almost forgot how exhausting it can be to talk for three full days. However, it seems like the biggest part of the training went quite fine, and the attendees were satisfied.
The most interesting part for me was to learn about the practical "real-world" setups in which those users were actually using packet filters, NAT, bridges, routers, etc. So basically it put me in touch with some of the more advanced users, and taught me about their particular requirements. This will definitely help during the further development process.