to answer the original question, its the Mark V cause its the next in the series of amps. Its like alot of products, version 1 version 2 version 3.. so on. this is version 5 revision 0, and its still a mark amp even though its based on 3 of the most coveted mark sounds, so calling anything else would seem odd. The mark series has a reputation that they want to associate with the new amp, and by putting the old names to the old circuits it gets more people who were on the fence to buy, (or not) since now they can get something very close to the older amp that they might have been wanting.
Regading soldanos being based on the SLP circuit and being more forgiving, i am not sure but i dont think thats true. marshall plexis had little gain, until cranked and every mistake you make is pretty out there, they don't cover up or forgive.
its a not so simple question of whether or not to keep an amp, its "do i like it?" and that changes day to day with most all amps. but good luck finding the tones you need.