According to one paper EBA (unlike aid) probably had a negative effect on trade
The main results show a negative effect of the EBA regime on exports. Otherwise, the combined effect of the EBA and aid on exports is positive, supporting an EU development strategy that includes both sorts of assistance, aid and trade preferences.
Another paper says
effects [of EBA] in terms of trade flows have been modest
And a 3rd paper...
Overall the results suggest preferences have a very small impact on trade, and negligible or even negative when we consider the scope for trade diversification. Therefore, it appears that the GSP system has provided a small effect on increasing exports at the intensive margin, but no effect on export diversification.
I couldn't find any papers estimating the effect of EBA on emigration... but assuming the papers quoted above are correct, EBA itself couldn't have been good for diminishing economic migration, or the effect was fairly negligible.