I've worked with it in two forms ....Great Plains in pervasive SQL and MS SQL.
If you have a choice MS SQL 2000 would be the best way to run it. (The pervasive ver needs reindexing every so often which isn't fun when month or year end balancing is in progress. Active links are a must)
Even though the software is Mid Enterprise sized software..the software is highly client AND feature modularized for licensing reasons (cha ching $$$). Because of the expense, a better wide scale and all inclusive package would be JDE Edwards or SAP. They have better scalability and supply chain support than Great Plains for not much more in OVERALL price.
Also, some of the Great Plains modules (such a MICR, check printing, and fixed asstes) are not easy to setup even though they cost extra. Customization will be required to get a lot of the reports and modules (depending on how many you're running) to work the way your company prefers.
If it is just going to be payroll, accounts payable, and accounts receivable with simple sales/inventory then QuickBooks Enterprise would be a better cost effective/time effective solution.
In any case, as an IT guy I always push for SQL based back end no matter what the package is. This allows for better resource management, disk space management, backup compatibility, administration, expandability, etc.
Also, whenever any new proposed software is presented to me I always ask the sales rep for access to their online knowledge base BEFORE the purchase takes place. The first thing I do is run searches for phrases like "known issue" and "limitation" to see how many hits exist for the current version of the software. I also check if any of the current known issues would pose a problem for any of the key features that would be needed. Also, it allows you to see how often the software gets updated and if a new version may be on the horizon (i.e. Why spend a lot of time setting up one version just to do a migration a month later?) If the salesman doesn't want to allow knowledge base access before the purchase then BEWARE!