Not sure about that. There are tons of people with successful high dollar SPS tanks that use instant ocean. Instant Ocean has a proven record and has been around since at least the late 80's.
What is this Fritz RPM? I've only been out of the game about 6 years. This sounds brand new. Do you buy it locally? Don't know that I've even seen it on any of the big online places. (currently shopping for a new 210)
Most of the LFS is selling it. Check around to see who is offering a special. It should be available at the show this weekend as almost all LFS are going to be there in Dallas. And Frits will be there to answer any questions too.
<hr />I was using red sea pro until I noticed all the tremendous amounts of brown residue it was leaving in my salt water mixing vat. Switched to Tropic Marin Pro and it mixes pure and clean. But it's a bit more expensive.