FY open (vertical): possible line of defence?

This is one of those really tricky lines for both players. No idea which player to name it after–HRF likes it but I’m not sure if it’s his originally. I have not got a surefire defence against it but can usually make life difficult for violet. Here’s the start of one line I’m working on:

1. F – X / 2. Y – N / 3. T5 – P / 4. N ….. I vaguely recall that for move 3, violet L5 to close the centre (H8rrru) is bad, but it’s not obviously bad, so I’d better actually go & prove that another time…

Obvious next move for orange is Y or L5 (I think Y) off the X — haven’t decided what’s the best orientation yet. In general, it’s vitally important for orange to play through the hole the moment he gets the chance — it’s too soon this turn, but I would recommend it on the next turn no matter what. The trick is to avoid messing up the nice 1-2 leak off the top of orange P by letting violet block both leaks simultaneously.

Achilles heels #1

The holed FY opener comes in two forms, depending on whether the Y is place running down or across. The ideal is for orange to play F or something else into the hole, allowing violet to wrap N around orange X & start squeezing from around the edges. It’s an excellent opener to play against inexperienced or midlevel players who don’t know how to respond. Unfortunately, as far as I can tell, it has a definite solution from orange’s perspective: this is the response devised by Bobby_Bob:

Looks bad for violet...

You also see Y for orange N, too, though I haven’t worked it out. Orange’s obvious moves are W curling around the top or bottom.  I’d advise hanging on to F, as that’s the best block on the top if violet plays W above.

If there’s an obvious flaw in the logic here, please tell me.  (The N is weak, for instance, but I fail to see a stronger move.)