One quote from the Sopwith Camel vs. Fokker Dr.I book:
"Most telling was the fact, tat german pilots were advised to escape an attacking Camel using a right-hand turn - supposedly the Camel's forte, yet one the Dr.1 could perform in a shorter radius that would eventually bring it onto the Camel's trail."
Sadly, there is no source for this mentioned in the book, but then again i never heard anything about the Camel outturning the Dr.I.
Also in the book, the Dr.I is said to not have the "Camel's vicious handling quirks", Ltn. Heinz Graf von Gluszewski-Kwilicki said "the smoothest lovely ship i could fly after the Pfalz and Albatros".
Even the Camel with the weakest engine is said to be faster than the Dr.I, even with the Dr.I engine working at full efficiency.
Climb rates were about the same for the 130 HP engine modelled ingame, with stronger engine, the Camel did climb better, with weaker engine worse than the Dr.I
Like i said, except for the Dr.I handling, there is no source given.