I think in your case it's hard to decide because losing TUI could be a big drop in productivity (I actually proposed TUI support for ruby/debug but it's too big of a maintenance burden).
But as I said in the end of the post, ruby/debug is going to evolve faster, especially with newer Ruby versions. So even if you don't plan to migrate now, I still recommend you to try out the ruby/debug features I mentioned, and see if they can benefit you in the long term.
I believe in the next year or two someone will make a TUI support for ruby/debug too.