They are both good helmets. I own a sweet full face, and I've tried the WRSI on.
WRSI makes a helmet with great safety features for a very good price. Hard to beat that combo, especially for people on a budget. The main downside of the WRSI for me was that it rode high on my head and didn't fit me well.
Sweet helmets are pricey, but they are awesome! I bought a sweet full face because in my opinion its got the best impact absorption, and it fits me perfectly, almost as if it were designed for my head. The sweet fits me noticeably better than my WRSI, and I think that a great fit helps keep a helmet snug on your head and improves energy dissipation.
I think the price of the sweet helmets suffers from two big drawbacks, one they are manufactured in norway where everything is super expensive to begin with, and two, the dollar exchange rate has slid over the last several years causing the US dollar price for the sweet to go up as the dollar went into the shitter.
Even though sweets are expensive, I think they are worth it. Its one of the most important pieces of safety gear I own, and it will likely last me for at least 3-4 years. If I average that price out over the years I use it, I pay more for creekboats, paddles, drysuits, beer, and gas on an annual basis.