I don't think there are any issues with Kies or Odin for flashing. I've flashed many times, sometimes 4 times in one day and I've never had any issues. There does seem to be the usual SD issues but I also think there is a USB communications issue. There have been many reports of data corruption while writing to internal/external SD with large files. I personally had an issue pulling large files off of internal/external SD. I think if this problem occurs while flashing new firmware it could cause some corruption that could be noticeable right away or after a bit of use. The partitioning on this device seems to be more sensitive than others and a hiccup while flashing could cause some major issues.
Darren Maunu (Synaptic_d)
Bell Galaxy S I9000M - CM9 Stable
Nexus 7 - CM10 Nightlies
Unlocked and debranded HTC Dream
Telus Galaxy S Fascinate - stock