Overheads reels are not consider the best reels for jigging for a couple of reasons,
When jigging with a overhead reel you are constantly balancing the rod because it naturally wants to spin back to a lowest point position.
Also, It takes you considerably longer to get your jig to the floor then it does with an eggbeater, this is very important because you wanna hit the strike zone straight away and with an eggbeater you literally get down to 100 metres deep about 2-3 times faster then with an overhead, which means you have alot more time to jig.