No plans to use time signatures. I haven't investigated into how accurate that part is but we can look into it.

I'm surprised no one mentioned that Melodyne comes with two activations. -If- you have two PCs (as I assume many do), I'd upgrade and check out the latest version on one PC and maintain the other as is for any showstoppers. 
 
Based on the few posts I've read, there appears to be issues with; 
1. clips with non rendered (i.e. still active) Region FX using V2
2. multiple clips within a single track ..? (recommendation was to bounce to a single clip IIRC?)
3. 64 bit version of V4 (recommendation was to uninstall and install 32 bit version.)
4. Substantially greater processing efficiency with the standalone version than the ARA integration within Sonar. (acknowledged by Melodyne but without a delivery commitment) 
 
I expect the V4 feature set and ARA integration in Sonar to warrant the effort. I've ordered a mine sweeper from Amazon and will be tackling this as soon as I can clear a few days. 
 

superdan54
OK now the more useful feature for me would be the ability to switch back & forth between the various tracks imported into Melodyne. As it is now, I still have to hunt down the specific region FX and click "open editor" in order for me to adjust it. Any news on if this will be implemented?

You can, at least in the Studio version.   You can view multiple FX Regions in a single Melodyne window, and display the active clip using the typical orange while the others are grey.   The only downside is you have to select the clips in the Track View instead of the Melodyne window.   I think that's not possible with ARA yet, or at least I think I read that at some point...