Whatever I am going to tell you, you may not believe it. LOL!!!
In Japan, we don't really go for pattern. We just go for colour. The Saber Tooth pattern shrimp usually will have the best and purest gene. This is due to much lesser cross-breeding and/or in-breeding. In recent years, all the gold medalists in shrimp competition are Saber Tooth pattern.
The PRL currently in the market are originate from JRB. The Taiwanese use the JRB to cross-breed with their shrimps to create those PRL we see today. After that they sold it to the mass market in EU and US. Hence, it is no surprise your Saber Tooth pattern shrimp still carry JRB's colouration.
For my that Saber Tooth patter shrimp, another affecting pattern is that she is about to breed. This is why her colour is more intensified.
Ah... I remember something that I wanted to let you know but always forgotten to. When you are culling/breeding PRL, do note that those with ivory colour (not yellow but more like very pale cream colour) carries more of the original gene. The whiter it is, the more Taiwan Bee gene it has. If you keep breeding all the ivory colour shrimp together, you will get more red legs than white legs shrimp.