The first heat exchanger you made is referred to as a "coaxial coil" or tube-in-tube heat exchanger, which is much different than a shell and tube hx. The shell and tube as well as the brazed plate modules are best to purchase rather than fabricate due to the complexity factor.
Brazed plate modules are generally more compact and transfer the most heat per unit volume compared to the other two designs. However, they tend to foul up with scale and contaminants faster. With your closed loop system, this is not much of a problem. But for pump and dump or any systems that don't recirculate the same fluid repeatedly, major maintenance issues exist.
A coaxial coil can rival the performance of the other two designs if the right materials are used, namely convoluted or rifled tubing for the center tube. This is known as a "high density" (or some trademarked brand name) heat exchanger. Note how close the OD of the inner tube is compared to the ID of the outer tube.
If common smooth tubing is employed, the overall length of the coax coil must be much longer for the same heat transfer capacity. This is known as a "low density" hx. Performace of a low density hx can be somewhat improved by running the refrigerant through a smooth center tube and the water through a convoluted tube on the outside.
Randy, what size and schedule of pe pipe did you use for your ground loop? Is it run in series, or do you have any parallel loops?
Congrats on the success of the system. I hope it serves you well for a long, long time.