I have the 100 engine in my car and have no issues going up hills at all.
In fact i have just done a mini service on it and it now goes like sh!t off a shiny shovel.
Never imagined changing filters,oil and plugs would make such a difference !
I've no experience of this engine, but it will depend a lot on the load (number of passengers) and incline of hill.
I remember many many years ago my brother in law had a sunbeam imp sports. On the straight it was very quick.
Come to a hill with a couple of passengers, and it slowed right down. Although that was an 875cc. engine
I expect the Bmax engine is a little more refined.