Assume everything else is kept constant.
1) no piking at the hips
2) piking at the hips
3) L-sit
I always strive to keep my legs perfectly vertical, but then I see people saying "legs went forward, but provided no assistance to the rep", implying that piking at the hips is acceptable. I thought legs going forward made it easier. But then also I hear that L-sit muscle-ups are harder. I'm really confused.
If anyone could care to explain the facts then please do. Thanks.