I think I like these - underwear are so difficult - all butts are different.  I would say they run just slightly small.  According to the size chart I wear a Small in NB.  In most underwear I wear a Medium.  I did order the Small, and they do fit.  I just ordered a different set of NB and ordered the Medium.  Even in the small there is no VPL and they do stay put.

If you want your synthetics to last wash in cold water and hang dry.  I also recommend NEVER using fabric softener of any kind.  It gums up your washer and dryer and even if you don't use it with synthetics, your synthetics are still exposed to it.  Plus, fabric softener ruins the absorptive quality of your towels and sweat-wicking and breathability of your expensive workout or outdoor clothing and who wants that!  Use white household vinegar instead.  Pour 1/2 to 1 cup in the fabric softener area of your washing machine.  Give it a month or so to get all the fabric softener out of your clothes and towels and you will be singing its praises too!