If the adventure is ready to go, other than enhancements a Kickstarter will, if successful, fund, would it not make sense to release the adventure as is now, for subscribers, and add the enhancements if the kickstarter funs, whether to the kickstarter participants only or also as an upgrade for subscribers? One further question - when will Adventure 7 release? If #6 is ready to go, presumably #7 is proceeding behind the scenes, and will be released "on schedule" regardless of whether #6 is further delayed?
For my group, we play slow enough (with other games interspersed) that release times aren't as big an issue - we'd have to get pretty speedy to move from somewhere in Dying Skyseer to needing #6 in a hurry. However, I can certainly empathize with GM's who have planned their games around a promised release schedule that hasn't been met.
I also think the concern expressed by at least one poster, that the erratic release of the Zeitgeist scenarios raises concerns about whether Kickstarter commitments, present or future, will be met merits serious consideration. "Underpromise and overdeliver" is a mantra for many businesses. If the promise had been one release every 8 - 9 months, and they came out ever six months, everyone would be thrilled. If the promise were quarterly and they were delivered three per year, everyone would be disappointed. Managing expectations, and meeting the expectations set, is more important than a lot of businesses realize.
For gieonpepys in particular, he has asked on numerous occasions about whether later adventures would be delayed, and has always been assured they will come out on schedule, so I can see where he would be feeling he may have been misled, regardless of whether he would agree (and I suspect he would) that the delays have not been foreseen, or even avoidable, at least in most cases. He's operated on faith, not only that the adventures would be released in timely fashion, but that they will continue to be great adventures as he has pretty much committed to running them, sight unseen. His game reports have, I think, been great marketing for the AP itself. And I suspect he is voicing concerns a lot of buyers, and potential buyers, likely share. It's tough not to take criticism personally, but I think the concerns need to be viewed in that light.