Ok, I did some more testing early this morning. I even read the Handoff programming guide and watched the Handoff WWDC session (more than I needed or wanted to know about Handoff at this point in time...). With that in mind, I did a bit more rigorous testing. Below are my notes. There is some unreliability on
both the iOS and OS X side, and I'm not sure what actions might triggered it. In both cases, toggling Handoff enable and BT restored Handoff functionality.
Pages on OS X: It doesnt need to be enabled for iCloud Drive, but the open document must be from the Pages folder in iCloud Drive in order to Handoff to iOS. On iOS, Pages must be enabled for iCloud Drive, otherwise it cant access anything. AND, you need to go to Settings > Pages (not iCloud Drive) and tell it to use iCloud (syncing).
It took 15 seconds for iOS Pages to get and open an updated version of the Mac open document. I went to Handoff on iOS immediately after making the last change to the Mac document, so it hadnt automatically saved to the cloud yet.
If I wait a few secs (15) for the Mac Pages document to auto save to iCloud Drive after the last modification Handoff was instant on the iPad.
When OS X flakes out, turning off/on Handoff, then Bluetooth (perhaps only BT needed?) restores Handoff to iOS. Took about 30 seconds after last change on iOS Pages doc to finish Handoff to Mac. I also had a situation where the iPad didnt seem to broadcast Handoff, but was fixed by turning BT off the on.
Switching apps to (iOS) homepage, Safari, then back to Pages, then using Handoff on Mac resulted in the current iOS document opening instantly on the Mac. The only time there is a delay is when there hasnt been enough time to autosave the document to iCloud. And yes, in the case of Pages, iCloud Drive is needed (and iCloud to sync). I opened a document with a section selected, then did a Handoff to Mac, and the document opened with exact selection made.
Different apps will use different means of transferring data and or documents. Just because Pages requires iCloud Drive doesnt mean other apps need to or do. There are several API methods for transferring activity data and documents. Documents should be put in iCloud, but a developer can use other methods of transfer (wifi direct or, if small enough, BT). For instance, using Safari for Handoff requires a minimum of data (can even have been sent via BT) to perform the Handoff, so there isnt any real delay at all - either from Mac or iOS.
I feel I've done enough with Handoff, especially Pages going between iOS and OS X, to know how, if it flakes out, to get it going again. It'll get better over time, as all new features have (for the vast majority) done.
Sidenote: I found when turning off (iOS) iCloud Drive for Pages, it also
disables the "Use iCloud" setting in Settings > Pages. When iCloud Drive is reenabled for Pages, the "Use iCloud" doesn't get reenabled, so you need to go and manually do that (Settings > Pages). It won't see any iCloud documents without both enabled.