When remodeling a bathroom, what is the difficulty/expense factor to convert it to a wet room?

I have a very small master bathroom (62" x 62"). It currently has a shower, toilet and sink. I’m planning to remodel it (without expanding it) and am debating whether or not to make the whole room a wet room, instead of using a shower tray. What would the cost multiplier be for this decision? Does it add significantly to the cost given the small size of the room? What are possible complications I should prepare for?

Turning your entire bathroom to a wet room would require an additional floor drain in the middle of the room, and hot-mop the entire room - not just the shower pan.

I have done this multiple times for my clients with needs varying from disability to terror-proofing for kids. This should not pose a significant change in cost.