Perhaps you need a different professional tiler if they are unable to answer your questions.

https://www.ceramictilefoundation.org/homeowners-guide-to-hiring-qualified-tile-installer

Well, I had the same question and was told by a Schluter salesperson that yes their tileable grate could be switched out later for the other because they use the same channel. I did not verify this with Schluter though so you may want to call them directly. We have the tiled linear drain cover.

It interchanges. But what no one tells you about the tileable ones is how very heavy, awkward, and dangerous that they are to remove to clean the trough. The regular ones are a bit of a pain to do that as well.

I have a tiled one that we hate and want to replace with a metal grate. Is this possible? My contractor said that the tiled grate isn’t interchangeable with another 4’’ grate.

You might want to look at Luxe brand linear drains: Luxe

They are just as well built as the Schluter drains, but at a much lower cost. I have two: one with a metal grate and one with a tile-in grate. I believe they have a standard drain pan design so that all their drain covers -- metal or tiled -- are interchangeable.