In a Ron video that I did back in October, he suggested leaving our toes tucked for Up Dog and I find that it is easier for me to do the pose this way in a fast paced class. Is there anything wrong with carrying this form of Up Dog into all vinyasa classes?
I have seen other instructors offer this option during vinyasa style classes. While this is not the traditional variation of the pose, if it works well for you in your transitions then it is fine to use in other classes. Just make sure you are able to keep your core and legs engaged enough not to over sway in the lower back.