There are corals that cost more than the Trident. Really.
OP - open ended question and there are a lot of possible answers. If you test daily and have an Apex already then it would make sense to buy one. It would save you a bit of time and you would get more test results by including Ca and Mg. Not sure if that is important to you or not, but it is what is going to happen. It would also allow you to test at a minimum 4/2/2 - 4 alk, 2 ca, 2 mg a day. So now you have more sample points.
If you don't have a Apex controller but considering one then this would be on the pro side of the list. To include Trident assisted dosing. Seems again like a win win. On the other hand you could reduce your manual tests to say once a week if the numbers are trending to what you want and save time and money that way also. People have been running successful tanks without automated testing for years - it isn't going to make it or break it.
It honestly is a matter of convince at the end of the day. Is it a good product? Yes, without a doubt they did a great job with the product. Some people do not like reagents but they have been around since the beginning of this hobby and they work. Reliable. I've compared my results with my manual and ATI icp's with similar results.
So for me it is a nice tool, saves me time, and since I already had an Apex it was an easy decision to make.