People switch all the time I switched from IO Reef Crystals to ESV Seawater System with no ill effects- plus once you do a handful of water changes your whole system is essentially switched over to the new salt but was done at a slow pace. Good luck with the new salt.
I wouldnt switch over without doing it slowly and keeping a good eye on it , especially if theyre that different in alk. Although a bunch of small water changes would gradually change levels where they differ, if you/your corals are happy with your current levels id do your best to keep them the same
Don't switch salt brands based on what the label says. The best way to find a good salt is to search the forums and see what people are saying about the salt they are using. There have been numerous write ups about the various mixes with graphs and everything else to help you make a good decision. I personally don't like red sea I think a lot of their stuff is cheaply made and low grade, there are far better and cheaper mixes out there.