Having now been on both sides of the druid ritual, I have some observations to make:
1) The wide-range visibility of a ritual allows people to buff up, group up, and go in with fire and steel - often against a single druid
2) The long duration and prohibitively high breakpoints for sacrifice make it difficult to shorten the duration of the ritual, often demanding that druids stay alert (full buffed and ready for attack) for as long as half an hour. Wormsight helps this somewhat, by offsetting the need for a druid to drink see invis... all the time.
These points are fine as they promote conflict and/or interaction. However:
3) The rewards are randomised and frequently poor, and there is little incentive to make expensive sacrifice to reduce duration for every single ritual, as much of the time the reward can be as little as 10 tinctures of clw.
4) The ritual interruption requires only a spellcraft check and a conversation, and takes less than a round to complete. In the time it would take a druid to potion up enough to put up a fight against a group or even a single full buffed individual, the ritual can be interrupted and the group can withdraw without conflict taking place. The druid can opt to chase, but has already "lost".
Reducing the base duration of a ritual, or making it less expensive to meet certain breakpoints for reducing the duration would address point 3 (or simply remove many of the weaker items from the drop tables). However, I feel this is a lower priority compared to addressing point 4.
I would like the conversation to interrupt the ritual to initiate a vulnerable phase that is AT LEAST as long as that of opening the King's gifts, where the interrupting party must remain stationary and defenseless for a turn (or more!). This necessitates defeating or driving off any defenders, and more importantly gives them the OPPORTUNITY to defend (and opens up possibilities such as waiting and ambushing a single person, if they are arrogant enough to enter a grove alone).