SD2 and 3 are the same with different dimensions. The Pro does not come with a case...just frame like you have depicted. I bought the SD2 and it looked the same. If you received enclosures with the first two, you made out like a bandit.
As far as the new ones without cases, this will allow you to build your own enclosure and it actually opens up more possibilities to modding, control tests between stock enclosures and mods, and even more important, they are FUN(!!!) to make! 
Plexiglass, a few M3x8mm screws, corner brackets, and two hinges (for the door) will go a long way and are cheaper than spending the extra cash for the Expert model.
Printit Mason and Printit Horizon printers
Multiple SD2s- Bulldog XL, E3D v5/v6/Lite6, Volcano, Hobb Goblin, Titan, .9 motor, Lawsy carriages, direct Y drive, fishing line...the list goes on
Filawinder and Filastruder #1870.....worth every penny!