As folks know who have followed this on the GCPBA listserv, there was quite a bit of chatter about this subject over there.
First though, a clarification of something you said. We've been in direct contact with Steve Sullivan. Unless he changed his mind in the last week, no actual decision has been made to implement this in 2015.
Back on point. At the time this first came up, we didn't have any serious concerns because the shortening of Spring trips was equally offset by an increase in trip lengths in the much sought-after Fall season. And in any case, nothing was going to happen right away. But after participants on our listserv got fired up on the topic, we discussed it in one of our Board conference calls.
You choose to portray the trip length change issue as a "loss in the Spring" situation, when it's really just as much a "gain in the Fall" proposal. It's an equal trade, and people have legitimate preferences that cut both ways on it. Our current position is that we dont think this is a very serious problem, but we wouldn't object if the Park were to make that change. We also decided that we're going to see if we can develop an alternate proposal that would include leaving April trip lengths in place, while adding to the length of trips in September.
Hope this helps.