I myself only had the PX100-IIs, so I can only speak for them. But I found them nicer on the lower frequencies than the Koss Porta Pros I used to own. PPs had slightly more sparkly highs.
The 238 however, this one reviewer says they are PX100s on steriods, so that's a good sign. However they are compared to the PX100s, not the IIs, and some people say the PX100-IIs are better than the first version (like me), so they might be on par (238 vs PX100-II).
It would maybe come down for comfort and portability between the 2 you are debating to get.
In that case, portability is in favor of the PX100-IIs hands down. And comfort with the 238s because of their earpads. Both are open, so not good for public unless you're a rebel
.
Hope this helped a little bit.