I had a scoot with an AC fired CDI... If the battery is very weak, you can kick start it easy... you can even start the engine without a battery using the kick start...
My Kymco has a DC fired CDI... If the battery is very weak... you are doomed because you need the battery to power the CDI...... now what is the purpose of that lever at the side called a kick starter?
A lot of new bikes, even small bikes, have the DC fired CDI... why change something that aint broken? What are the advantages of a DC CDI versus the AC CDI?