We went through this process two years ago. We looked at HP RISS, Symantec Evault and Quest Archive Manager. We decided on the Quest solution and are very happy with it. Symantec gets high marks from Gartner and for good reason; it was just more expensive and Quest gave us all of the above you are looking for and it was less. Archiving to date only half of our users has reduced mail store size by half. We went from 2.6TB to 1.2 TB after archiving.
I’ve seen several demos and talked to all sorts of sales reps and found EMC’s EmailXtender and C2C’s ArchiveOne email archiving tools are the best. I like the ArchiveOne solution better, but take a look at them and compare.
I would appreciate it if you told us what you’ve decided on.