Time zone support in CETS New Blog Defaults plugin

Last weekend's DST shift brought to light a problem on my sites. We use CETS New Blog Defaults to pre-configure our blogs, including the time zone setting. However, the plugin appears to set the "GMT offset" preference for each blog, rather than the "Timezone string" pref. The difference, as best as I can determine, is that "Timezone string" appears to know about DST changes while "GMT Offset" simply offset the time based on GMT.

I'm now faced with making timezone changes to more than 200 blogs. Any suggestions would be appreciated. Thank you!