Actually graham is more mobile cause it has a MA mode with V boosting and does not fall in altitude while boosting in air.
Also, about the saviour, it has 4 second boost, there should be nothing wrong with its boost duration not shorter nor longer)
While I am at it, might as well post the F91 after nerf boost pool
Normal mode : 3 secs
R mode : 5 secs
With bio com skill: + 2 secs