Bolter is spot on the money. You only _need_ to swap your marker if your current one has problems with chopping/reliability, or it's unable to hit the ROF cap, or is so inefficient that you're running out of air each game, or you find it difficult to tech.
Anything else is just about the bling or your own curiosity. Fine if you're minted, but on a shoestring make the most of what you've got.