Last time I updated pages I lost features I liked and was unable to open some pages files. Now I see the features I liked are back but I have a lot more files to worry about. Will I be able to open files created in 5.2 if I upgrade to 5.5.3?

Within reason, Pages v5.2 documents are forwards compatible with Pages v5.5.3. Apple introduced the single file format document as a default with Pages v5.5.3 which is not backwards compatible with Pages v5 on Mavericks.

However, they also provided a File > Advanced > Change File Type > {Single File, Package} menu that allows you to change the current Pages v5.5.3 document into the backwards compatible Package type document. You would follow this transformation with a File > Save operation to complete it.

In your most recent post addressed to me, the use of the term, “Within reason,” implies the following:

• Yes, Pages v5.2 documents are forwards compatible with Pages v5.5.3.
• But… Maybe not.
  • Any release of Pages v5.5.3 has proven to exercise amnesia about its own v5 genre documents, and may fail to open them. Reason unknown.
  • Any release of Pages v5 is the poorest quality, buggiest software that Apple may have ever released. Therefore, unpredictable is baked in.

I simply refuse to use Pages v5 (any release) for serious word processing work.

PS: Not a good idea to start a new post specifically addressed at a single individual. Your follow-on post to this thread will bump it to the top of the posts, and it will get read again for more recent responses — most likely by anyone, including myself, that had previously contributed.

Pages v5.2 can export to Word (.docx, .doc), so no need for laborious copy/paste to another word processor.

Probably time to have an introspective discussion: “What do I need in a word processor,” and “How will I use it?”