I love Roto flats on long scale basses but the short scale sets are horrible IMO. They are far too light gauge/floppy IMO. In fact, I could say the same about all Rotosound short scale sets. The Roto 66 roundwound sets are actually even worse. Possibly the worst set of strings I've ever played.
With D'Addario Chromes it's the other way around. I find the long scale sets too stiff and inarticulate, but that stiffness can be an advantage with the lower tension on short scale basses. I actually like the short scale set, even though D'A Chromes are a bit clanky/harsh sounding in the upper mids for my taste.
I am not sure if the worst, but definitely not on the same level of the long scale Rotosound sets. I love my SM77 and BS66 regular sets, but on my short scales, both "equivalents" were indeed not very successful-last year's Rotosound 66 experiment on my Bronco was utterly sad, and I was compelled to take them off almost right away, as the E would not intonate. Not old stock-their newer, sealed packaging. The Sheehan "Swing Bass" set has never had bad strings, my short scale Roto set just seemed poor quality. i love Rotosound!-they just need to update these strings, or at the very least at newer gauges, but I simply doubt they ever will, content to put out the older sets I am sure some may love after years using them. But I agree they are not the same, even if branded as for "short scale", and it's not just their floppy gauge that differs.
Did use Chromes on a shortie eons ago, but my preference for flats now are the Ernie Ball Group I flats, as they do exactly what I wish the 77 flats were-a very nice, stiff tension that still isn't too much due to the shorter scale, a perfect feel, and nice articulation (not bright, but with good mids.) Because I do use a Xtender, the thick E works for me, never getting floppy.
If they made thick Swing Bass 66 for short scale instruments, I would be all over them!!!