And I get 70MB/s out of each port of my Qnap TS-509 Pro *today*. And I have tons of services running on it, like a mail server, web server, blog server, SlimCenter feeding all my Squezebox and Transporter clients, etc. Would never think about exchanging it against a Drobo! Never! It also already has iSCSI should I need it!
And if you need 8-bay: http://www.qnap.com/pro_detail_feature.asp?p_id=109
Yes, that looks nice. But it's over $1700 so as I said, similar solutions will cost MORE.