I have this wonderful Greek place near work - they do marvelous soups (not all of which are anywhere near Greek, but all are good). Their avgolemono uses meatballs.The shredded chicken is what I got in Greece (Athens and the islands) and in most restaurants. I suspect the meatball variant is either Lebanese or a regional variant.
A risk when adding pasta or rice to any soup is the sideways step into a stew/soup hybrid. Stoup.When I made it the last time, I had a bit too much orzo, and it came out a tad thick. Absolutely nobody complained.