The D is for Dual Link (4:4:4 or 1080p/60) version of the monitors. Both monitors have dual input, dual output connections and supporting dual link hardware from factory, the D option is a password enable for $2000 additional above and beyond the base price of either monitor.
The top end LCD CCFL backlit model in Single display is the LVM-241WL which has a new reduced black shift panel. This monitor is MSRP $7,995. This is likely the monitor you should evaluate for your application unless you need quad display for some reason you have not indicated.
The LQM-241W is the quad split input version of this with additional enhanced software which is a priced at MSRP $9,995.
Once again, if you have any questions that are sales related and should be made off-list, please contact me directly at the information below. You can also download PDF spec sheets at my website. Although I am the authorized Northeast US reseller, I can assist you to locate the product in Europe.
Regards,
Dave
David Radin
Vidkey, Inc.
radin@vidkey.com
914-373-9242
http://www.vidkey.com