LMP2 are faster than DP...
And by quite a lot, too, which would make whatever "equalization" of the two types of cars most interesting. Given the new masters, my suspicion would be that the ALMS P2s would be dumbed down to a Daytona Protobrick level of performance. Same for the ALMS GT cars vis-a-vis Grand-Am GT.
If you want numbers, ALMS and GA have raced twice at the same track this year. at Mid-Ohio and Road America. At Mid-Ohio, the top GA Protobricks were around five seconds a lap slower than the ALMS P2 leaders -- and little more than a second a lap quicker than the ALMS GT leaders. At Road America, the difference between DP and P2 was more like 8-9 seconds, and the top ALMS GTs were less than a second off the DP leaders.
Earlier, someone posted that the DPs appear to have about the same cornering speed as the P2s. I can only guess that person was either watching on TV or in a hairpin corner, because I've stood at several different corners at Road America, and I can see the difference in speed. Even without the factory Audi/Porsche/Acura prototypes any more, the current ALMS P1s and P2s are viscerally exciting to watch up close (when driven on the limit). The DPs -- eh. And the sound doesn't help, either.