I really like SemanticMerge, it makes total sense, although the diff experience is unlike other diff tools in terms of immediacy. But I think it will be another great tool to add to the arsenal when you need to pull out the big guns on crazy diffs.
Its biggest limitation on real projects is that it works on a single-file level, while all the interesting stuff happens on patch level. You may browse their forums to get an idea of what else is missing.
That said, I wish all the best to Codice and I really hope that they continue to invest in this tool.