I don't think the Majin boost would do much for Dabra. I think Vegeta was anomaly with the boost, and getting his power brought out beyond the limits. If Babidi did that for everyone, Spopovitch would have one-shotted Videl. I think He remains the same level of power, Vegeta loses.
Dabra would still stomp. Only thing i could possibly judge his power by is the boost vegeta got (granted the chance that dabra's would be much smaller) so there should not be a cell games vegeta - cell games goku difference in his power when he is under the spell in my opinion.
I could see Dabura having gained a large boost from Babidi's control. Spopovich and Yamu seemed to gain a bigger boost than Vegeta did, so I assume it'd yield greater gains the more evil a person is, in which case Dabura would get quite the increase. I'd still see him winning without resorting to magic though.