Yes. The human brain can adapt very well. If you progressively go from 1x to 1.5, 1.75, 2, 2.5, you don't quite notice the change and they seem to be taking at a normal speed.
I plan on raising it soon to 2.75
Discussion
I max out at 2!
Do you feel you retain the info?
Yes. Unless there is external noise or distractions or the audio quality is bad. It's not like most podcasts are discussing String Theory
Frankly I cannot listen in normal speed anymore. It would be different if I needed to write transcriptions.