Well let's not call that a rant, but you still have not said how:
…since Pages 5.5 (such as is is) plays better with Numbers 3, I am willing to tolerate Pages 5.5.
In fact after having made such a bald statement you then turn around and confess you have no idea how. Why did you say it then as it was the substantial reason you claimed for using both? This too often is what you get. We here can detail the over 100 missing features and the innumerable bugs in Pages 5.5.1, but people such as yourself just say "its better". Not really a rational debate is it?
Look you can keep using Pages 5.5.1 and Pages 3.5 if you think it is somehow "better", but on examining the facts when that clearly is not true, it just makes it another example of the Stockholm Syndrome that I like to refer to my son, the Psychologist.
The ongoing incompatibilities I referred to are the continuing mutually incompatible changes to the file formats that mean people not using the current System can not open the files. Something that along with the long list of missing features just makes continuing with the iWork suite ongoing churn with an almost certain prospect that your files will be ultimately unusable.
Progress on updating Pages is glacially slow, as I have pointed out multiple times at this rate it will be 2023 before it catches up with 2009. Pages Data Merge did not come from Apple, it is a clumsy and awkward fix using AppleScript and is not a shining beacon on the hill of good things to come. If you have to resort increasingly to patches like this to get common things to work, you are more expert at wasting time than at using Pages. Which I think is the real nub of the problem, not knowing much on the subject, it is all the same to you.
Peter
btw There is no "iWork '14". Further, there is no reason you can not keep using iWork '09, a format that can be shared with users on Snow Leopard, Lion, Mountain Lion, Mavericks and Yosemite and even cleanly exported to Word .doc/x something which eludes Pages 5.5.1 users too often.