In both cases during the "learn the tool" phase you end up spending time having to figure out how to do things, understand workflows etc.
In the TUI case though, you can usually tweak that workflow and configure it to match your brand of thinking. It costs a little more per instance up front, but after that year (or whatever time period), you get a much less frustrating experience, and the oddball things your particular workflow requires have been smoothed out - where in the GUI you'd still be frustrated and a bit fumbly or suboptimal, so you continue to pay the penalty for it over time.
It's really about how you amortize the total time put into using the tool.
In the TUI case though, you can usually tweak that workflow and configure it to match your brand of thinking. It costs a little more per instance up front, but after that year (or whatever time period), you get a much less frustrating experience, and the oddball things your particular workflow requires have been smoothed out - where in the GUI you'd still be frustrated and a bit fumbly or suboptimal, so you continue to pay the penalty for it over time.
It's really about how you amortize the total time put into using the tool.