I also use Tropic Marin Pro Reef and have been for 5 years. I love it and don't plan on changing anytime soon. The only think I'd wish they'd change is the alk is a little on the low side, around 7.0 dkh.
Thanks Dan for the info on RSCP, I knew their alk was really high but hadn't heard of the inconsistencies.
As far as difference between salts, they all contain a different amount of ca, alk, mg, pH, and the tons of trace elements. So I wouldn't say they are all basically the same. Remember to switch salts slowly.
Nick D.