I would say the opposite, actually.

"They" as a gender neutral singular pronoun is, to me, perfectly natural. I use it dozens of times a day as such without noticing.

Spivak pronouns, on the other hand, are blatantly marked, and were I to come across them in writing or speech, I'd find them very distracting.

Thanks for alerting me, indirectly, to the Spival pronouns. I think they're a good, minimalist approach to a fix, but agree they will look distracting until or unless they become commonplace.

I guessed - correctly - it would be the same Spivak who wrote the excellent Calculus textbook.

Spivak pronouns have all the benefits of a singular "they" with all the drawbacks of introducing a new set of pronouns into an established language. My experiences with programmers tell me that getting a large group of people to change syntax is not easy.

Spivak pronouns do indeed come with drawbacks (as do all proposed solutions for gender-neutral language) but I put forth that said drawbacks are minimal. The pronoun set is intuitive to English-speakers and I've found that brief explanation, if any, has been required no more than once per person before they can easily grok my usages.

I agree that from a perspective of getting more people to use them the drawbacks are greater but from the perspective of understanding the drawbacks are essentially non-existent.

I agree with you: Spivak pronouns are definitely easy to understand. I just see getting more people to use them as key to having a standard third person gender neutral pronoun in English.

One benefit that _they_ has over _e_ is that it is distinguishable from _he_ in those variants that tend to drop word-initial _h_.

Another benefit that these novel pronouns can't pick up is that _they_ is the normal gender-neutral pronoun in use by native speakers, and has been so for centuries. The Spivak pronouns are not. If you have to explicitly teach pronouns to adult native speakers, or if using a pronoun requires deliberate thought, then there is something wrong.

I can think of two drawbacks of the normal gender-neutral pronoun, but I can't see how they are solved by Spivak pronouns, in fact, one of them is much worse.

1) Some people think that singular _they_ sounds awkard. However, considering the Spivak pronouns are a novel coinage in a closed class of words, it's almost certain that more people would find them more awkward than the normal gender-neutral pronouns.

2) There is a possibility for ambiguity with the plural pronoun. However, I can't think of a situation in which it wouldn't also be ambiguous with an distinct singular gender neutral pronoun.