Serial coils should be good for VV/VW devices that are able to push high voltages. I haven't experimented much with it myself, but I feel that I should.
In theory the reduced current should give you less power loss in the coil legs, and in the "no-res" coil posts, and the points of contact between post and coil. This should in turn give you an atty that is more resistant to becoming hot, cooking your juice.
If the regulating circuit is as effective or more effective at high voltages than at low voltages, it should also lead to better battery life. But that is a pretty big "if", and naturally depends on the design of the particular circuit in question.