@DoubleAA, the way I read it, he says that it is not kasher l'chatchila. However, even if it's kasher b'dieved, it's passul l'chatchila. I am also well aware of those ways of writing letters in a way in which they are certainly not traditional, namely budget mezuzot, although some argue that those are also passul.

@NoachmiFrankfurt What do you mean by kasher b'dieved, passul l'chatchila? The word Passul means b'diavad.

@Daniel, something which is not kasher l'chatchila might be kasher b'dieved, although it might just as soon not be. I'm searching for an image to use as an example of a broken פ which would be problematic for all authorities.

@NoachmiFrankfurt I'm just pointing out that you're using your words a bit imprecisely. The word פסול means even b'diavad by definition.

@Daniel, perhaps I'm not communicating as effectively as I had thought. How can something which is פסול always be בדיעוד? For example, a Torah which is found to be passul (chas v'shalom) cannot be used until it is corrected. In fact, I have heard that this applies even when no other sefer is available.

@NoachmiFrankfurt Perhaps I am not communicating effectively. I am saying that if something is pasul, it is pasul even b'diavad. If something is no-good mi-d'oraita, but fine mi-d'rabanan, pasul is not the correct word.

@Daniel OH! Now I see what you're saying! Sorry about the wire crossing. I was trying to say (without halachic terminology, so bear with me) that the way the Ch"Ch views the form of the letter פ, if it is written in the manner in which Chabad and some other communities writes, it would not be permissible at the outset, however it would be acceptable after the fact.

EDIT: In my previous comment, strike mi-d'oraita and mi-d'rabanan and replace with l'chatchila and b'diavad

@Daniel, I often hear passul used in that context. What would the correct term if not not passul? Also, I am considering moving this discussion to chat, if it is going to last any longer.

@NoachmiFrankfurt not kosher l'chatchila

Technically, the term kosher is also b'diavad, so you could just say kosher

although I hear people say "Kosher l'chatchila" even though it's not a technical usage of the word than I hear people say "pasul l'chatchila"

I have never heard someone say pasul l'chatchila, kosher b'diavad

@Daniel This is the way I've heard folks refer to something in this context.

@NoachmiFrankfurt Hmm I guess we just have different experiences

I've never heard that

@Daniel I guess so.

@NoachmiFrankfurt I wonder if that's common or not

I posted in Bam to find out what other people's experience is

Just out of curiosity

@Daniel I'd like to see too, well… I'm headed there