From my experience, the DURATION is unchanged.
For something starting before daylight savings begins and ending during daylight savings you need to list at 6pm for it to end at 7pm. The DURATION does not change.
That is, up until now ... you never know if eBay might try and get clever and 'fix' the times. (I spoke to a seller who swares they listed something at 9pm for a 10pm end ... but it's showing as 11pm. I'll need proof - as they can get lost in their work.)