Only my opinion:

Using the transposer is an easy way out. Now that I am older and my voice is changing I am using the transposer more often.

I know that are players who play in Db or F# and use the transposer constantly. Wrong? -- No nothing is wrong. And some players do not use the pads, or change instrumentation. It is a matter of what you wish to achieve.

I took a few piano lessons years ago. When I asked the teacher how can I get comfortable playing in Eb? Play all your songs in Eb for a few weeks. Eb was no longer a problem.

What I did:
1-Took an easy song with few chord changes and played it in all the popular keys. C,F,G,Bb, and D. Then I gradually added Eb, Ab, A, and Db.
2-I learn the relationship between chords and the different scales in each key. A song in C Major sometimes goes to other keys. Ex: Body and Soul. C major, Db Major and B major. I had to use a bit of discipline, but I gained a lot of freedom.

Please keep in mind that I played guitar for many years before going to keyboard.

John C.