Castrol's oils are not mainstream in the personal use HDEO market; they are more prominent in the commercial market.
Generally, any of the brand name fluids are perfectly capable of "normal" OCIs, and most of them are capable past that duration. The "big three" (Delo, Delvac and Rotella) have the lion's share of the personal use market. But that does not mean Castrol, Valvoline, Pennzoil, Kendall, and many others are not good products.
I have used the dino Tection Extra 15w-40 and was quite pleased. I'm sure the Hypuron will do a fine job presuming you're using it in a properly-spec'd application. And that price is what I am seeing currently for retail shelf dino fluids in my area.
I'd say go for it!