Cross Up with HK or MK

Just wondering why the cross up with HK is soo much pickyer to land compared to the MK one. Its like the timing and space has to be very detailed where as on the MK its not as much.

I think its because the hits with the foot section, while the version has a wider colision size, from the foot to the knee

just tested it, you can do the cross up with the HK its just UBER picky, rather stick to MK then