I'm not familiar with the Cosse Violetto burgundy but they look interesting. I am growing Coco Blue for the first time but unlike my Emerite, Fortex, French Gold and Ramdor beans they are not yet setting. Maybe they are a late developing variety.
But I will also agree that the French Gold are excellent yellow filet beans along with Ramdor.
The advantage to the pole filet bean varieties over the bush ones seems to be that they don't quit until frost as long as you pick them. Easier on the back as well!! They also continue to be nice and crunchy even if you miss one and it gets really long.
I wanted pole varieties and found them hard to find. Most places sell the bush varieties of french fillet beans. And I was looking for color as I wanted to try someting new. These work out perfectly for me.
No consensus. Some pole beans do have great flavor that is matched by few bush beans. But it depends on your taste buds. My wife and many others will not eat a pole bean. I have grown a few different varieties in my time and judged on my taste buds and ease of production Contender for bush, Little Greasy or Kentucky Wonder for pole.The old Mountain Half Runner has the best of both worlds.
Bean varieties I have grown since 2005. http://s294.photobucket.com/user/farmerdill/library/Beans?sort=4&page=1
Yes. There have been bush beans with strings in the past, but I have never found a variety introduced after 1920 that was not stringless. There are a few stringless pole beans but most develop strings at some point.