I had the coolflo, never had a problem. Just put a prefilter on it. To hydrolock an engine you literally need to submerge the filter in water. Torrential downpour with no driver foglight will do it too.
As for cfm's "copy." Its not really a copy, just a better design, in my opinion at least. That's what I have now and I think its better than the coolflo I had. I don't have the aem bypass valve, just the prefilter.