Yes, I like it. Though I still need to find a rosto to be allowed by my guild to join
1 hour is a good timeframe. It does not lock the map too long for people needing to do their thing on the map (haidir or harving etc). But it also seems to be a nice length for a battle: you can adjust your inventory on it (1 hours worth of HE's/LE's/etc and if you run out midway next time you can adjust the amount a bit).
I have been thinking about point 4 ('Not enough people ') in your initial post:
You might get more people to join if you also refer to the next event in the current announcement. Something like "Tomorrow same time will be (a+d/2)<110". Or, if possible, a line with all the next events for every grouping ("next monday ((a+d)/2)<80 next wednesday ((a+d)/2)<110)"). That way people can plan ahead (time wise) for the event.