I absolutely LOVE my MKV:90!!!
BUT....
Does the MKVII give you more?
A lot of that is going to depend on what you are looking for in an amplifier. The Mark VII is a more modern amp, which introduces features that the latest Mesa offerings have had. It has a build in Cabclone IR, and each channel has its own setting. It also has MIDI switching capability, so it can be more easily integrated into a MIDI setup. Both of these would also be possible with the Mark V using items like the Cabclone IR and the MIDI Matrix or something similar, but that means you have an additional cost, and setup time.
On the Modes side, that is kind of a toss up. It depends on which modes you like the best. The mark V definitely has more Modes, but the mark VII duplicated the FAT and CRUNCH modes on channels 1 and two, so you have a bit more flexibility in setting up your amp, at the cost of some versatility. The Mark V has the channels pretty much set up as Clean, Rhythm / Lower gain Lead, and Mark series Fury. The Mark VII has both clean and dirty options on channels 1 and two, and puts the classic Mark Sounds on channel 3. BUT, it also puts the new Mark VII mode on Channel 2, so you can have it WITH also having the Mark modes on Channel 3. So I guess you get a different kind of versatility with the Mark VII, which is that while you have less modes, you can set up the amp in a larger variety of basic formats.
Where you LOSE functionality is the previously mentioned versatility, as well as things like the power amp and overall volume controls, as well as the EQ. Each of the channels has a further voicing switch to modify some or all of the modes. The Mark V has the "preset" function for the EQ, so you can have a different EQ for each channel, and also have one set up with a manual EQ. Then there is the power amp settings, which have the "Class A single ended" mode, which I LOVE. Then there is also the ability to use tube rectification on channel 1 and 2 in the 45 Watt mode, and the Pentode / Triode selector for the high gain channel. Add onto this the Bold / Spongy Variac, the overall master volume, and the solo control, and you have what I think is a var more versatile power section.