They are fast as hell. They are definatly worth the extra money. If you are a beginner I wouldn't recommend them. They can make learning to ollie difficult. Once you get the hang of ollieing these bearings would be great.
Ventures are light trucks.
They are also low trucks. Low trucks are better to do flip tricks with. They aren't the most durable trucks. Grind Kings are heavy trucks made for grinding. They are hard to adjust.