Backup to Disk with Nexsan

We are in need of upgrading our backup devise. Over the last two years the number of servers we support has grown to over twenty. We aren’t on a SAN yet, but will most likely be there soon. First, we would like to upgrade our backup system. I recently found Nexsan: http://www.nexsan.com.
Has anyone implemented their Disk to Disk backup solution or had any experience with this company? Their products sound great. Any advise would be appreciated.