He liked it.
My cat's struvite crystals increased on this, after having the wet variant for weeks. We realised he wasn't drinking enough, having got used to the high water content of the wet food. He liked the taste and ate it all happily, so after 12 weeks of the high dilution S/O variant I am confident that he will do better on this when we try again, and will then be on it for life. Royal Canin have been very helpful and would recommend this food for struvite crystal dissolution.