They are indeed your only choice. Most waterblock manufacturers only do reference designs, only EK does the most non-reference designs. This is what I've said about them: they put quantity over quality.
That galvanic corrosion was unnatural, it should not have happened that fast. Perhaps someone mixed aluminum with the stainless steel parts?
I have some (a lot) of store credit left over and was thinking about investing in better RAM. Would this be a worthwhile upgrade? Will they run at stated speeds? And, can I watercool them?
Not really. Alphacool and EK make waterblocks for the Dominator RAM, but I wouldn't really bother as RAM doesn't put out that much heat. If you want to do it for aesthetic purposes, that's your prerogative.
Haswell has been shown to have limited CPU benefits with RAM faster than 1866 mhz CAS 9. If the RAM is rated 2400 mhz, it should run at 2400 mhz but your CPU's IMC might not be good enough to handle the overclock (typically it is though). I would attempt to overclock your Ripjaws to 1866 mhz CAS 9. If you have the itch to burn some money, get more RAM, not faster RAM. Playing with RAMDisks can be fun