I don't like detuning the E string on a 4 string bass, it just confuses me. I like to know where the 3rd, 5th , 7th, and octave are without having to think. Consequently, I feel more comfortable with a five string if I'm playing anything below E.
I have also never detuned any of my 4 string basses to Eb standard, or D standard as I think the shifting of the notes on the fretboard would possibly confuse me, though I might try that one day.
I play covers and the key of a song is dependant on the singer so I am, quite often, playing songs that were originally written/recorded in E, but we transpose to Eb or D. If the original bass line makes good use of the open E, for instance, the fingering becomes more difficult on a fiver as I will then have to fret the Eb on the B string. This may or may not be problematic, depending on the BPM of the song.
You pays your money you takes your choice. I prefer to use the fiver, if I have to, warts and all, rather than de tune.