Integration with Microsoft Office
Overwhelmingly, SMBs use Microsoft Office. The solution should integrate with the popular office suite.

Microsoft, of course, is pushing Domino.doc owners to migrate to SharePoint and this is their key selling point. But SharePoint isn't a full document management solution either, and since a number of Domino-based document management products offer excellent Office integration, Microsoft's claim to SharePoint's utility is rendered moot.

Web-based
A Web-based solution allows you to share information with those customers and partners who don't have the Notes client.

Also, look for Web-based products that will edit in-place files and attachments (negating the manual requirement to download to make modifications).

Document lifecycle
Manage, control and share a document from creation, publishing to archiving, and destruction.

Robust security
This goes without saying, but we'll say it anyway. Any document management solution must have manageable security levels from the top library straight down into the individual documents.

Easy to customize
It's all about being able to customize. This is the biggest extra cost, the biggest thing to pay attention to, so make sure you can get in their and tweak.

Scanning Integration
You should be able to connect to your network scanners ("MFP") and automate capture routing and delivery.

Notes and Outlook email integration
You'll want good email integration. As a bonus, some solutions will let you drag and drop messages and/or files from email and relate them in context of the documents

Audit logging and tracking
Any solution you install should easily track all the changes (who, what, when) made to documents and folders.

Versioning
Likewise, any solution you put in place should provide a rich, deep methodology, plus allow you to roll back versions and be integrated with archiving

Migration tools
Migrating from Domino.doc could be a challenge. See if the partner has a tool to make your life easier.

Financially viable
Review how long the business partner has been in business, and how long their document management solution has been available on the market. This is especially important these days.

Archiving and review policies
You may need to automate your government, industry and organizational compliance requirements.

Finding a solution
No matter which solution you go for, make sure there's a free trial. It's always a good idea to get a good feel for how the product works before you go for broke on an installation.

Despite all the advantages of a Lotus ISV document management solution, why don't some organizations just start at document management, rather than dabbe in basic collaboration?

I've found, among those customers I've talked to, that they often start with basic collaboration solutions because document management solutions are perceived to take too long to plan for and deploy, be license cost prohibitive for mass use, and be too hard, complex to use.