I haven't had any problems with my sfh chicks. then again i'm hatching from other peoples' eggs... apparently better than average hatch rates too. 70-80% usually, even with shipped eggs.
on the first bunch, i lost 1 the first day, and 1 to drowning because i left the brooder door open and he fell in the pond. the next hatch were from shipped eggs, 7/10 hatched. I know bulldogma lost a few, but that was due to power failure, rather than anything else. 4 from this last hatch, all doing well. (out of 6 eggs). and i've got 10/10 shipped eggs to go in the hatcher this coming week, due the 18th.
I do know that they seem to grow better with a liquid multivitamin in the water for the first few days to a week, and my other chicks really like it too (bantam cochins and LF dorkings). can't say that's why i haven't had problems, but it sure isn't hurting anything. if anything i think the vitamins are encouraging them to drink more. give them fresh water, they just look at it. add a few drops of vitamins, and all of a sudden everyone's drinking.
also, a lot of it might depend on the nutrition the parent birds were getting, as to how the chicks fare during growth, hatching & so on.
a couple people have speculated that the multivitamins help the sfh, since there may be something in sweden's soil/food/water supply that's lacking here in the US. it's just a theory that has yet to be proven or disproven, but apparently some vitamin deficiencies can cause stunted growth, curled toes & other symptoms... maybe someone else can give more input on that. i didn't bookmark the pages where it was mentioned. (in this thread, if you read all the way thru you'll find it).
edited to add: i haven't had any sfh shipped to me, other than hatching eggs, and 2 'teenage' pairs that came up from Alabama...
side note: she later warned me that all her roos got agressive (so she got rid of all her sfh), but i don't see it in either of these boys yet... redneck's a snuggle love (the one that got stepped on by a horse, is almost totally healed, but not fully feathered back in yet). the girls are friendly but not under foot, bubba, the other roo, is like the girls. friendly, unafraid, but stays out of the way. Redneck has figured out he can hitch a ride on the feed bucket and get a free meal while i'm carrying it down to the feeding station. (has to be horse-proof or maggie eats it all!)