Hatmonium is not at all suitable for Carnatic music because it can not render gamaka (complex blending of notes back and forth at varied speed and levels) which

Hatmonium is not at all suitable for Carnatic music because it can not render gamaka (complex blending of notes back and forth at varied speed and levels) which is the crux of that system. Hindustani music has only limited stress on such complex treatment of gamaka. So it is widely used in Hindustani music.