I'm not so sure about all the comments about X pollination with bumble and honey bees when the article written by Dr. Jeff McCormack, former owner of SESE, clearly stated that most X pollination is done by sweat bees, aka Halictid bees, which areso tiny they are difficult tosee..
http://www.southernexposure.com/isol...es-ezp-35.html
Jeff's comments about isolation distances are quite conservative since at the time he was producing seed for SESE.
Just adding that it used to be thought that all true currant, S.pimpinellifolium, varieties have exherted stigma's but it's turned out that only about half of them do.
Carolyn