apparently the parasite parts have been around a fairly long time, however they are very badly documented by maxim, i came accross them purely by accident. i think from the little i can remember from what i read that your spot on with the timing issues 3v0, but it seems the vast majority of people give up with them and go for the non parasite type, as you can use them in eigther mode with no code change....i will see if i can dig up the posts i found on it
i found this in the datasheet " The 1-Wire bus must be switched to the strong pullup
within 10 μs (max) after a Convert T [44h] or Copy Scratchpad [48h] command is issued, and the bus
must be held high by the pullup for the duration of the conversion (tconv) or data transfer (twr = 10 ms)." alto of the trouble i read about related to the timeing