We also have used both on a split trip, and I totally agree that the TS meals are a wash and the snacks and QS are "free", but the problem for us is that we really don't WANT to use the QS credits, and since the signatures cost two TS credits, it doesn't necessarily make sense for us.
Actually, I say that because the advent of the Dining Plan is when they started to make all the menu changes. If it isn't caused by the dining Plan, then why did they happen at the same time?
I hear you about QS. We tend to pay OOP for signature meals although this trip I think we will do one signature meal using the DDP. One other will probably be OOP and at least one other will be while we're not at BCV.
Menu change all the time at WDW. They did before this DDP and continue to do so. Some change on a nightly basis.
We've only dined at Olivia's a handful of times. The changes there seem to have really struck a bad not with OKW regulars. Perhaps those changes were a result of the DDP but it seems more likely to me that it was a change in management at that restaurant which was reported on the DIS. Also some of the changes seem to have removed particularily unhealthy choices. WDW certainly seems to be headed in that direction but again DDP probably has nothing to do with that.
As for all the menus being the same, it just isn't the case at the restaurants we frequent. The menus aren't remotely similar.