Two suggestions to benefit members: one may well involve too much work; the second is the easier (for an expert) alternative.
Have you considered offering, as a Poll special, a good espresso blend from the various single-source beans currently on offer? It would be good to have the input from the experts out there who source these beans.
Alternatively (and probably more practically), could you suggest what could be a great espresso blend from the beans on offer so we can use that advice to assist in our Poll ordering? Just two thoughts. ...
I look at it this way: theyre all good for espresso !
Seriously, in my experience, Ive offered a "sample" of a coffee blend to a number of work colleagues, and it had huge variance in acceptance, which lead me to believe that tastes are very personal. That means, you should try beans, try blends, find what you like, and then try some other beans too :)