That is exactly right, the quality of the speakers is just as important as that of the guitar and the amp. I have been told that the modern Marshall cabs have Chinese speakers in them, I don't know if that is correct. The speakers in my cab are Celestions, my amp head is the only bit of gear that I have ever bought new, I love the vintage stuff, my cab is from the 80s.
Isn't great to have that much gain on hand, what I like about the Mode 4 is the flexibility in sound, you can get classic Marshall tones but also more modern tones that suit downtuned guitars. Rock and Roll