They are different.
I had a DC-5 combo about 10 years ago. It was my first Mesa amp, The clean/crunch channel is voiced like the Mark series. The clean channel is good, very clean and it has a pull "crunch" knob which makes it very similar to the rhythm 2 channel on the Mark IV.
The lead channel is, like I said, more voiced like the recto´s, but a bit smoother. It was very dark and thick sounding, but I felt that it was a bit too compressed for me. It has tons of gain, but it got too compressed as you turn it up. It kind of made every guitar sound similar and I thought it lacked a bit of dynamics. It ends up sounding too soft when the gain is cranked. It was good, but not great.
The graphic Eq was as useful as ever.
I have played a studio.22 and a caliber.50+ briefly and I felt it was more for me. Very tight and warm but with a good bite too. It sounds more like the old Mark series amps. And it´s great for a Metallica or Dream Theater sound and like you said, Meshuggah used it (they have used recto´s too) so it good for that kind of sound.
It´s not as versatile as the DC series because of the shared gain knob (and eq), which makes it hard to get a good clean sound at the same time as a heavily distorted sound. But for heavy gain sounds I prefered the old caliber series to the DC series, perhaps because I prefer the Mark series to the rectos. Make sure it has the graphic EQ though, it makes the amp much meaner.
Both are good, but for just a great distorted sound, I would get the caliber.
If you want versatility, the DC is better.