Thanks for positive replies!
I guess those Sedo's big acquisition offers more often come from end-users, and other, smaller offers more often come from domaining gamers. However, I've seen some funny big-buy domains from Sedo simply redirect to buyers' homepages with their original vapid domains, or just get idle there--those domains' owners want to resell their expensive domains?
A big disadvantage for sellers on Sedo is there seem no ways to get to know buyers/bidders, what size of their business? What are their likely purpose of acquiring a domain on Sedo? Knowing nothing about a bider on Sedo makes it indiscreet to make sound counter-offers.