Any reason not to take an OBP?
 

I am looking at train travel from Dresden to Regensburg and one of the options I am considering includes a leg on an OBP, which I've never taken before.

What is an OBP?

I'm assuming OPB, which is the private operator Oberpfalzbahn, on its OPB1 route from Marktredwitz to Regensburg.

A local may be able to advise better, but it's a standard German regional operator using fairly standard rolling stock (https://de.wikipedia.org/wiki/Alstom...a_LINT#LINT_41) at a relatively genteel pace. If the connection works, I'd personally go for it.

It seems that for passengers, the only difference from a regular DB regional train would be the branding of the stock, although these private operators IME tend to have cleaner trains, some may even have free wifi and ticket checks seem to be more common.