Many jurisdictions require a licensed HVAC person to do the install. I have the necessary equipment, vacuum pump, manifold, etc from working on automotive A/C, but chose to go with the MrCool DIY system as it has prefilled lines and compressor and doesn't require an HVAC person to make the final hookup. My initial location for the compressor was on a rooftop and the idea of hauling all the equipment up and working in a precarious location didn't appeal to me. My final location was on top of a porch roof with a fairly shallow pitch so the location wasn't nearly as demanding but I'm still glad I went with the DIY system.
I see that MrCool has made some changes to their DIY system, offering different lengths of lines and line extensions. Previously, the only option was a 25' line, which was the reason I went with the porch roof installation (I needed 35' to reach the ground). They are also a bit more cagey about installation requirements, probably coming from the legal beagles.
The most difficult part of the installation was the prep work. I had to make a plywood backing board to mount the indoor unit as I couldn't tie into two studs. The coolant lines exited the attic space and into the soffit in an inaccessible location which required the better part of a day of hand labor to make a sufficiently sized passage for the lines. My compressor hangs from the side of the house rather than sitting on the porch roof. To mount the compressor made shims to match the taper of the siding boards to provide a flat surface for the mounting brackets. With all that work done, the actual install was less than two hours start to finish.
