In my limited WWI experience, 1 on 1 the DVII is a much more dangerous plane than the DrI. The DVII can actualy stall fight and perform a rolling scissor not that far off in feeling from an early 109. The DrI and the Camel both suffer horribly in a co-alt merge if the DVII pilot uses his speed to start a vertical rolling type fight. The F2B is also a good contender in vertical rolling fights, far better than either the Camel or DrI.
Lengro and myself, who have dueled each other easily 5,000 times since we first met in AH, did alot of 1 on 1 testing when the WWI planes were released. While it was possible for any plane to win in any combination of the four, the D7 had a major advantage verticaly if the planes are flown by equal pilots.
DVII vs DVII fights were the closest to anything we do 1 on 1 with the much more advance WWII planeset.