To offer an opinion based on the original question "Does the Mark IV sound like the V?". No it does not.
I have tried to get a close comparison to both amps, swapped tubes from the V to the IV and played through the same 412 cab. The V is voiced differently than the IV. There are some similarities with the Lead channel of the IV and the CH mark IV mode, but they are not identical. The V offers a greater degree of different tones in all channels. Very versatile. I had the same assessment between the Mark III and the Mark IV, where the Mark IV was more versatile than the Mark III since there was separation between the lead channel and the clean and rhythm. I almost miss the Mark III, but I am happy to get feedback from the new owner who is very pleased with it.
I doubt that I will ever sell the Mark IV, I do enjoy playing though it from time to time, plus it is easier to transport since it is a combo and not a half stack like my V. However, I have been considering getting another amp, was considering a Carvin V3 half stack, but may opt for a V combo instead. If I get a V Combo, I may sell the IV.