Have you tried any IEMs before? Which of them have you found comfortable? That might help.
Build quality is decent. Nothing extra-ordinary. The cable is rubbery, housing is plastic. But in most cases, as long as you take proper care of them, they would last long. I have read about numerous failures of SoundMagic PL series within six months, but also have a friend who is using PL30 for over 2½ years as his primary day-to-day IEM.
Fitting should not be an issue. The housing is small and should fit most people easily. They are comfortable due to their light-weight. But they are shallow fitting and cannot be inserted deep like straight barrel IEMs. As long as you choose the
correct size tips and use the
proper insertion technique as described
here, you should do fine. But, as a side-effect of shallow fit, they would not isolate much. But, wouldn't a lesser isolating IEM be more suitable for jogging than something that blocks all ambient noise?