This is just my experience, I am not discounting anyone elses opinions or experiences with alpaca. :} That said, I have several 100% alpaca soakers and they work great! I have checked DD underneath to see if she was too hot and I felt no difference in skin temp than with regular wool. Also, these are my fave soakers so they get used alot, and have not stretched more than my others. Same thing with lanolizing, the only difference I have noticed is alpaca can feel "slicker" than reg wool, but then it does normally anyway.
The difference may come from using Huacaya alpaca wool or Suri alpaca wool. Huacaya has alot of crimp (some domestic alpaca farmers specialize in crimpy wool), Suri is the luxury alpaca that has no crimp and can streeeeetch alot. Domestically produced alpaca is not quite as fine and shiny as imported, but it is a wonderful product!
I would ask the seller a few questions about the wool. If it was Huacaya wool then they might be worth trying. :} Hope that helps!