You need to know the head tube angle when choosing the best rake offset. A 40 mm offset is not extreme for modern road bikes with steep head tube angles. It will give you more steering trail than a longer offset. Longer trail means more stability. I have an Ouzo Pro 40 mm rake offset on my Trek that has a 73.8 HTA. I prefer the 40 mm to my previous 43 mm.
A 40 mm rake offset would be extreme for a layed back HTA as found on many older frames.

Al