I used to use Reef Crystals for Years and everything was fine for a NON-SPS only tank.
However when I started up a SPS only Tank, I wanted lower ALK levels (7.5-8).
The Few salts available at the time (or known to me) had much higher ALK 10-11dKh. And what was worse alk would SWING on each bucket/box purchase.
To me having a salt with ALk close to my tank (or lower which could be raised) was important since I've had times where I wanted to do a Significant water change.
For example if for some reason a 50% or higher Water change is needed, using a Salt with High Alk would be (somewhat risky).
I did learn from a LFS owner that he USED TO USE higher Alk Salts, and brought it down with a touch of Muratic Acid. He doesn't do that anymore.
That's why I switched to Tropic Marin Pro. Mostly for Alk. I also did a couple of ICP tests on Tank (last was a month ago) and each time result came back perfect.
So I've come to trust the TMP mix (for Elements and Alk), and with a new SPS Frag only 110G Tank, I'm hesitant to use anything else.
The only thing I don't like about TMP is the PRICE.
I did discover that the Red Sea Blue Bucket Salt has an ALK of 7.5, so something I will consider since price is better.