Currently running freehand on new 27" iMac Retina with El Capitan.
Install Parallels 11.
Install OS X Server from CD (call apple to order $20-) use remote disc from any mac or CD drive.
After install - update via software update to last 10.6.x version (this will install Migration assistant to utilities folder)
Install Parallels' Tools via action menu in parallels
Use Migration assistant to transfer user folder & applications folder from former Snow leopard computer or time machine backup.
All Rosetta dependent apps will work without need for new passwords etc... b/c all info will be transferred via migration assistant.
Screen resolutions up to 5120 x 2880 available