As far as I know, there really isnt much advantage at all for a trials rider, it gets in the way while holding the seat out front and less importantly adds a bit of weight.
In my opinion its not really worth changing to a rail adapter and bike seatpost setup unless you are breaking standard seatposts. I’ve recently changed to a Thomson seatpost and rail adapter because I bent then broke my standard seatpost.
i fully agree with tony. if you are breaking seatposts then you might consider the upgrade, and if your upgrading from the standard post there is a lot of directions you can take (including reinforced posts). the rail will affect your seat-out for street/trials but is really comfy for long distance/muni (because of the angle adjustment availability)