Cameron, if the extra coil is vertical it would be very problematic when refrigeration velocity fell during low load conditions.
This is not a cut and dry, right or wrong.
The article posted indicate some of the reasons that they may not be desirable but it can also be noteworthy that commercial ice machines are designed with a specific line set if they use a remote condenser and if you modify it, you screw it up!
The article is basing its opinion upon installers that don’t use certified HVAC technicians to start up the equipment once it’s installed. These line sets are sealed and you simply bolt them onto the indoor and outdoor unit (breaking the seal). This eliminates having to evacuate the line set with a vacuum pump, eliminates potential water and air contamination, etc. but in any case in HVAC technician should evaluate the startup to ensure proper installation and charge.
As Charley pointed out, there’s a lot of different ways you can install an HVAC split system. If you have the condensing unit on the roof and it’s too high, you have to modify the piping design to ensure proper velocity to lift the oil back up to the compressor. If a startup technician isn’t available to do this job, you don’t have a clue what you just installed.
Any dip across the crawlspace of the refrigeration line causes a potential oil trap. It is noteworthy to put in your report but is not necessary to listed as a defect unless you know for a fact it is. And there’s no way to tell the oil level in a compressor without cutting it off and dumping the oil out.