I myself certainly think that if you can do something easily why complicate it ? It was made clear to me in the study of my guitar playing. I love playing chord melody on my guitar and one of the masters of this style of guitar was a fellow named Barry Galbraith who was a studio musician back in the 1950’s. He was a most talented player but always said that the simpler you make the playing the more you will get out of it. His interpretations of many Standard tunes shows this off.
I think ventriloquism can follow the same route. You should make it as simple as you possibly can and it will reflect a good job with some practice. If you write your script you should try, if possible, to avoid all the sounds that are so hard to do without moving your lips. If the sound is unavoidable then you have no choice but there is always other words to use.
