A body may see occasional cold damage to some kinds, balling or other difficulties with the flowers of others. The lower end of the Valley has a history of getting very cold (-12F to -14F around Springfield-Eugene) during the coldest winters, tea roses (and most of your Hybrid Teas etc., for that matter) aren't likely to come through in one piece below around maybe 5-10F. During the 1990 winter up here, when it got down into single digits many roses were damaged. Otherwise, if they don't know this place they probably should go look at their collection:

Heirloom Roses is located in the Willamette Valley of Oregon, one of the
finest climates in the world for growing roses. Located just 25 miles
south of Portland, also known as the “City of Roses,” our gardens
feature thousands of beautiful, fragrant roses.

http://www.heirloomroses.com/info/about/directions/