What is the main reason people upgraded their electronics like ESC and what not?


I have a TT01D coppermix drift spec, I have an itch to upgrade something and wonder if I should dump the original ESC.





On a side note, my coppermix has been acting funny lately, the throttle and steering act up from time to time, like when I was drifting around a turn in a steady manner, all of a sudden it has a mind of its own and went full throttle all of a sudden, or turn itself in different direction anybody experience weird behavior from their RC?