Ive heard the MK1 Solista many times. I cant recall hearing the Mastersound integrated but others, who have heard my Italian integrated as well as those of interest to you, tell me that Mastersound shares many similarities with my New Audio Frontiers. If thats true, I would say that the Viva has a much more modern tube sound, while the Mastersound would be more intimate. If there is an 845 tube that you favor, find out if its compatible with the Viva first. It seems to me that the Viva too often rejects tubes that my friends try. The Viva Mk2 is a very different amplifier from the MK1 and from what Ive heard, much more than just marginally better.
