Facit Postal X Or Ix Or VIII Or.what Are The Differences?

Hi,

I've been thinking lately of buying a FACIT Postal catalogue for learning more information values of Swedish cancels, but I'm unsure how new of a catalogue I need.

I see there's FACIT Postal X (from 2020) Postal IX (2015) and older ones, as a new catalogue is released every 5 years. Of course, the cost cah change quite a bit from an older version versus the newest version.

I'm wondering about what are the appreciable differences between the newest versions and some of the older versions, specifically for postmarks from 1870s to 1940s? I just want to be sure of what I'm getting, so I don't get too old of one, and then regret it because it's missing some important coverage that was added later.

Looking at FACIT's website for Postal X, I see: https://www.facit.se/postal_eng.html

NEW: The catalogue is now in hardcover with a ribbon bookmark.
NEW: The catalogue is printed in colour for the first time.
All sections are updated.
NEW: Sea Post Cancellations.
Major updates of the Swedish Covers section.
The section on Steamship Post Offices Along the West Coast has been thoroughly updated.
The Postanstalten Postmarks section is updated with the earliest and latest known postmarks.
Updated membership roster for the Swedish Stamp Dealers Association.
624 pages.

The thing is, I don't know much about Sea post or Steamship Post offices, or postanstaltn postmarks, so I don't know if I'm likely to come across those normally or not, so I don't know if having those extra additions are worth the extra cost of the newest edition....though being in color could be nice...

Anyone have any thoughts/opinions/recommendations? Does anyone know if some of the postmark types one if more likely to come across got changed enough to warrant getting it?

Thanks!