The jury's still out on this one. Penon Audio couldn't help me (they don't sell FLC8S eartips). Emailing Lend Me Ur Ears goes like this:
Me: Do you sell FLC8S eartips?
Them: This is an automated response. We will get back to you within 48 hours.
Them (48 hrs later): Yes.
Me: Ok, great, I'd like to buy some.
Them: This is an automated response. We will get back to you within 48 hours.
Them (48 hrs later): Ok.
Me: Great, so how do I order them?
Them: This is an automated response. We will get back to you within 48 hours.
Them (48 hrs later): We will need to send you a PayPal invoice.
Me: Ok, so would you please send me a PayPal invoice?
Them: This is an automated response. We will get back to you within 48 hours.
Them (48 hrs later): PayPal invoice sent.
Me: Pays Lend Me Ur Ears via PayPal.
Them (48 hrs later): Can you please confirm your shipping address is the one on your PayPal account?
Me: Yes, that's the correct address.
Them: This is an automated response. We will get back to you within 48 hours.
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Still no eartips, but maybe (?) they're being packaged up and getting ready to be shipped any day now?!?
It's a great shame these are so difficult to buy; they're actually really good eartips. I have to eat humble pie here and admit
@Flcforrestwei was right about the extra treble extension (beyond 10 kHz) that these give. It's not a huge effect - but it's noticeable.