I suddenly noticed that the men around me seemed to be singing the soprano part transposed down by however many octaves seemed appropriate, so I switched to doing that and found it to be almost laughably easy in comparison.

This seems to be very common in the congregation I attend. Some men sing bass or tenor, but the majority sings soprano-transposed-down-a-couple-of-octaves. (And incidentally, when there's no accompanying music and people are singing a cappella, they tend to transpose the music down about four or five semitones, so I wonder whether most hymns are really set "too high".)

I typically sing bass, FWIW. And I like four-part harmony hymns; unfortunately, there are a fair number where the non-melody part aren't particularly melodious and mostly provide accompanying chords -- singing a total of three or four different notes during the course of a piece is not particularly satisfying, I feel.

I reckon most hymns are set a bit high for the 'average' woman's singing voice, at least - on the unscientific basis that an untrained singer is most comfortable with a chest voice, and around a C' I for one have to go into a head voice, which is a bit of a strain (for this untrained alto-ish not-very-good singer, anyway!). Most hymns seem to hit highest notes that are C' or D' - so people transpose down to avoid those? At school we always had piano accompaniment and had to sing at pitch, and the singing was definitely quietest if the melody hit a D' or above.