I live in Zone 3A Canada and planted Warzawa Nike in mid-2003, in a partially shaded location. Although it has not grown as quickly as other specimens located in full sun, this clematis has surved well and this year, 2004 grew to about 1.5 m and produced about 30 blooms. I find this particular clematis delightful in that it produces flowers reminiscent of Jackmanni, but larger, palm sized flowers!
I have noted "General Sikorsky" is available here, and regret not yet planting it. The vendor's tag bloom photo looked "true blue" as does the picture on this site.