I don't find they result in pulls, but I do find they're a little more delicate in other ways e.g. the stitching holding the tie together can come apart where it comes under strain in the area you knot, especially if you're like me and undo ties rather harshly instead of with care. This has happened to me with other ties, but usually only after many years-worth of wearings whereas it happened sooner with my grenadines. But it's a five minute job to tack them back together, and I have learnt to remember to be a bit more gentle with them than my other ties, so that should forestall further occurences. Oh, and to answer the other part of your question, this doesn't happen with knits, only grenadines.
(pre-empting the obvious rejoinder: no, they're not poor quality grenadines. Or at least, they're from one of SF's favourite sources. But in this case, I think happens to be the same thing and I really like their ties in general, so have no axe to grind).