Cross runner beans

I like the idea of allowing varitys of runner bean naturally cross and keeping seeds year after year, this year i bought Mergoles and celebration runner beans , which of these vairtys should i havest the seeds from this summer to gareentee a cross breed seed and not end up with self fertilized seeds (beans)

 

I thought I read somewhere that beans and peas can, can, self pollinate before the flowers are fully open.
Not sure if that is true but to make a sure cross will involve removing the male parts of each flower selected as a seed parent before it can self pollinate.

 

Breeders have crossed French and Runner beans and these include Moonlight and Firestorm among others.

 

Runner beans tend to self fertilise.
I would be inclined to grow a plant of each away from the crop for the kitchen. You will need to decide which to be the pollen parent and which the seed parent. On the seed parent remove the male parts (stamens) and isolate from potential pollinator with a little mesh bag or similar. Then taking a small paint brush transfer pollen from the pollen parent to the female parts of the seed parent. Again isolate the seed parent flower until the bean begins to develop. Then harvest the beans from the flowers you pollinated after they have dried off.

 

Given the probability that you will harvest and enjoy the bean pod rather than the embryonic bean seed, what advantage do you seek ?