Griggs reactor dissolves 100% the CO2; yes you understand how it works. If you see microbubbles in the water you are losing CO2, that is why people choose reactors over diffusers.
There are alot of commercial products, but NONE of them are as reliable as a Griggs. Its made using commercial grade PVC pipe. CO2 gas can make plastic brittle over time, many of them break. Think about this... if your reactor springs a leak, your whole tank gets emptied on the floor.
Read the reviews of various reactors on amazon and you will see a small percentage of reviews where plastic reactor broke, flooded, etc.
I have not tested the reliabilty of all the commercial reactors, maybe gla has come up with a new gizmo... I did the reasearch on this, wanted to buy something but then found out that PVC griggs is the best. Nilocg happens to build them and sell them.
Regarding the regulator I am no expert at all. I bought a cheap one from ebay and its working great. I suppose higher cost may have better reliability or adjustment. Idk.