I'll put in a good word for Nexus 7; not super-efficient on paper, but feels nice to use because it shifts well, with nicer gear intervals than Nexus8/Alfine 8, and pawl drive rather than mushy feeling roller clutch drive.
Nexus 8 'red band' models have roller bearings on the planet pinions, like Alfine 8, so have the same gear ratios and are comparably efficient.
SA 5s hubs have a wider range than 3s hubs but are a lot of trouble for a slightly wider range.
Apols if this is obvious but if you fit a larger sprocket to SA 3s, so that the high gear becomes 'normal' this makes first gear into a reasonable gear for climbing. This is an inexpensive way of avoiding the issue.
cheers
I didn't know you can still find Nexus 7 hubs for sale. I have SA3, SA5 and Alfine8. Of all these the obvious one on paper is the Alfine and with 2:1 ratios (44/22, 38/16 etc) you are fairly well placed for most normal use, a bit short on the top end perhaps but low enough for most uses. I don't entirely trust mine but that's because it only cost me 30€ and I don't know its past history. Gearing is acceptably close, except at the ends (where it doesn't matter so much). (I think I'm on 32/17 at present but it might be a 16).
My SRF5 W is quite nice to use in a different sort of way, but fussy, fiddly and, I would guess fragile. I need my reading glasses every time I need to take the wheel out because it never seems to go back in quite the same way and I can only see the yellow dot with close glasses. 44/21 or 22, I would need to look to be sure. It's on a steel 80's race frame for a bit of fun but I don't use it as much as I should.
The AW is on a "vintage"style bitza and runs 46/24 which gives gearing for getting up Limousin hills. Reliable relaxing ride and doesn't need anything over the 67"top (I think that's what it is, about 5.4m in post Brexit currency - although I had to look that one up, it doesn't mean anything to me
) The old style Sturmey trigger just below the brake lever is also a much nicer thing to use than the SRF5's ratchet that I have mounted on the stem (lhs means that the lever can't go into sensitive body parts during crash stops). The Alfine has now been fitted with a twistgrip (on flat bars) which I find easier than the rapidfire trigger with my arthritic thumb. The 5 is going to get a barend shifter.
Of all three the one that does most work and that I definitely would not want to lose is the Alfine.
Edit Late idea. If your friend is already running a SA 3sp, have they considered simply putting a second sprocket on to get some lower gears? Something like 18-21 (the sprocket combination used by the Sachs 2x3 Torpedo, although others are possible) works quite nicely. Three tooth differences seem to split the gaps; I have not tried working out the bigger sprocket differences.
