The Mark V:25 and Rectoverb are pretty true to their big brothers. Tonal differences are the same. There are comparisons on youtube.
The Recto is darker at low volumes and sounds best when played loud, it sounds big, huge and surrounds you. The bass may a be a bit muddy when chugging and so a slight bit of tubescreamer tends to tighten things up.
With the Mark, it is a Mark. Focused, aggressive and tight. IMHO the Mark V:25 sounds better at bedroom volumes but the volume knob pretty much needs to be near zero. The mid boost function on channel 1 is nice for classic rock crunch tones. This one also has cab clone built in.