Using SmartVault for my seventh year now.  Have not used DMS.  90% pleased with SmartVault and will continue to stay with them.

Only faults I've had:  cannot print multiple files at once within SV.  Have to drag to Windows Explorer, which allows you to print max 15 at a time.  But when clients upload 80 documents from their crappy multi-function printer/scanner, it slows the process down.  Price, prior year they required a 2-person minimum.  It basically doubled the fee for sole practitioners.  Although you can get temporary tax-season licenses.  Finally, some clients struggle to use it as compared to my prior portal.  But most have no issue.