It's not reliable. For an option that you'd want to use against Noel's DP, you'd want something that will definitely work no matter how many times you screw it up.
You won't be able to tell she used 4D until she throws the move out itself, by which time you'd have already thrown out 2B. 4D's not the only option though; she could have chosen 2D, which goes over 2B. For an option against Noel's DP, you'd want to use something that works on every DP option she has so that she's forced to block. 5D is optimal in this case because of how it works on every option given you're close enough. 5 active frames makes 5D more likely to hit than with 2 on 2B, so that's a plus.