Do you think Shukendo is better than Mikkyou? I personally prefer Shinto, but I guess it's all a matter of taste. 
Shukendo is a mixed way of Mikkyou and Shinto.
Its a clever way.
But, some says that its not easy to learn both and failing to master both.
I personaly I dont believe it. But... who knows? Each person has their belief. Boodoo is mixed way also(African and Catholic) and powerful.
I personaly like Shinto more too, because all the mantras are in Japanese and easy to give those influence to my underconciousness.
Any spell should work better with the native language, i guess.
Since your mother tongue is not japanese, I think its not clever way to practice it.However, If you like their philosophy,I understnd it.