I have the SHL5 and will be listening to the 40.1 this weekend at my friend's place driven by Leben CS600. If the space is huge I would say the 40.1 is the way to go as the bigger speaker will throw a bigger soundstage and sounds bigger than the SHL5. Although the Harbeth is said to work well in small spaces, they do need some room to breath to sound good, especially with the 40.1 that may have bass problems in smaller to mid-sized rooms. A 17'x19' room would be quite good for the 40.1.
Alternatively, you can try a subwoofer to reinforce the bass of the SHL5. I have the SHL5 in a big space and the subwoofer made an appreciable difference to the overall presentation as the speakers are set up in free space away from wall boundaries for optimum soundstaging.
Alternatively, you can try a subwoofer to reinforce the bass of the SHL5. I have the SHL5 in a big space and the subwoofer made an appreciable difference to the overall presentation as the speakers are set up in free space away from wall boundaries for optimum soundstaging.