For the sake of a tenner, would certainly go with the warhead. As the above poster referenced, you should get a snappier semi response. Also the efficiency should be higher, so get more shots out of the same battery. Which if you are using certain AK stick lipo batteries can be a plus.
The ASG motors can also be a bit bulky. Have had fitment issues in the past with certain motor cages. Although it was only one or two brands. It can also cause difficulty with some pistol grips. No fun to have to remove the stickers off the motor and sand a pistol grip to fit.
The motor tabs from what I gather have been improved on later batches. They also seem to have reverted to a more traditional set up than the wires based system. The later while handy for certain set-ups was an absolute nuisance for others e.g. MP5 style grip. Just take it slow during the install and be careful with wire placement (To echo Hamster).