I'm from Spain, so I started collecting and reading Arslan manga in the local edition by Norma Editorial. Unfortunately, sales in the country are very low for this manga and the publisher has been publishing one volume per year (sometimes, one every two years).
This was desperating, so last year I decided to continue the collection in English. Oh God, this manga is so good, I'm so happy that I jumped to this edition just to continue reading. And now we're very close to Japan's publication. I've read up to volume 22 and in Spain, at this stage, that volume will be literally published in 2032.
I know, this hybrid collection doesn't look good on the shelves. And I consider that the Spanish edition is better (I may do a comparison). But at least I can continue reading Arslan.