I don't own an xray but having seen them perform, i would say let your current bearings die on you first, then change to ceramics. having good ceramics such as ones boca, will certainly leave you impressed. better than steel in all aspects except for keeping out dirt for sure in my opinion.
My recommendation would be to do a search. There are very many (and I meany very many) threads on this topic that have been written about.
Bottom line is yes, a good set of ceramics is worth it and NO, you will not necessarily see a performance increase with ceramic bearings.