I worked in a music store back then. The DX7 was KING for sure but we were a Roland Shop and the D-50 was pretty F'n awesome. I don't think it's apples-to-apples though. Wasn't the D-50 less of a synth and more of sampling board?

Yes and no. I guess the best way to describe it is that it was more of a half-step towards wavetable synthesis in the sense that it utilized ultra-short samples of the attack and sustain phases of the envelope to achieve something with greater fidelity than nominally possible with FM synthesis alone, but well short of what you could achieve with, say, a Korg Wavestation. It was an interesting product of its time.

I did a huge amount of D50 programming. The actual digital synthesis was not particularly impressive (limited architecture and weak filters). Multiple voices ('partials') could be layered in interesting ways - quantity over quality! The synth sounded great because because of the samples and the built-in effects.

You can listen to each sample if you try programming a patch. Some are short 'transient' samples, others are looped. The 'chipmunk' effect is really evident.

The D50 was the first of the new wave of 'S&S' ('sample and synthesis') synths that had nothing of the depth and mathematical interest of FM synthesis.