If "full text" setting is selected, I think WP should put the full content of post into "description" field when RSS feed gets generated when full text is selected, no?
This is a matter of considerable debate in the RSS community, but the general consensus is no, description is a *synopsis* of the content only. That's what it says in the spec.
Admittedly, content:encoded is an addition to the spec, but if you're going to have both description and C:E, then having them actually be the same thing doesn't make a lot of sense.
Podpress is putting the full feed in the description specifically because iTunes is broken in this respect. It should really be reading the content:encoded for the full text, if it's there, and only use description if C:E is not there.