All RTG(classic) have 4th level shine. Any RTG that has shine higher than 4th level is considered HBRTG (XBxRTG). Those HBRTG with good XB genes might have 6th level shine. In market terms, they are different due to shine level is higher than a normal classic RTG. Overall they are all classified as Scleropages aureus . I've never seen an HBRTG(RTG) with shine crossed. I've seen a few at 6th level shine, but wouldn't you consider something with 6th level shine an XB?
nowadays most of the RTG's today are produced thru selective breeding, i saw a merlion gold (HBRTG x XB) at 8 inches they already have gold specks on the 6th level.. give it another two years it has the chances to cross..