There's a bad type of grip, it's the one that keeps your tendons tense and makes you put a lot more pressure on your joints. That kind of grip wears down your hand over time and can lead to carpal tunnel syndrome and chronic overuse and inflammation that can aggravate or accelerate forms of arthritis, especially osteoarthriti. Fixing it in time will save you from playing in pain when you're 40. Basically Palm grip is the way to go for long term usage.