SHL5 is a great speaker for it's price. IMHO the M40 or M40.1 is worth more than 5 times the cost of SHL5. Matching a sub to SHL5 should close the gap towards M40.1, but dialing the sub is a tedious job. I've tried to dial 2 AR subs and also a James sub, and in the end, took them out and preferred without the subwoofer.
In the beginning of getting the M40 in, I thought I preferred the sound of SHL5 compared to M40. But after listening to both for a month or 2, I found that the M40 is giving more details in the treble, midrange and also the bass. I've also compared the P3, C7, SHL5 and M40 in my room. On vocals, P3 is the king. All other speakers lost to it when playing vocal tracks, but that's all it excelled at. P3 sounded sweet and crisp might be due to a lack of bass. M40 might not sound fuller and sweeter might be because it had more bass. That is IMO.
The M40 or M40.1 requires big, powerful and great amps to drive them "BEAUTIFULLY". These speakers will show all kinds of flaws with lesser amps.