With regard to MS Valentina -- STAY AWAY!!!
I took a trip with them last month, and the problems were legion:
1. Despite having had to cancel the trip just prior to ours for mechanical reasons--and pulling the ship out for dry dock repairs--one of the two engines failed after one day. That meant that instead of 6 days of diving across 3 islands, we got 5 days of diving across only 2 (couldn't get to Roca Partida because it would have taken too long with only one working engine, and then had a 2-day--rather than 1-day--journey back to San Jose Del Cabo).
2. Despite losing 15% of our diving--and paying a fuel surcharge on a much larger amount of fuel than actually used, given the abbreviated trip--the company refused to give any refund whatsoever. They only offered $300 off another trip on Valentina, a boat I wouldn't get back if you paid me.
3. Randomness: It was really weird how things happened only sometimes. Hot water on the deck shower? Sometimes. Power on for the pneumatic drying tools on the camera table? You had to ask. Hot chocolate after the 7 AM dive? One day yes--thank you!--but never again. The promised "snack" after the 10 AM dive--since lunch usually didn't come around until 2:30 PM? Chicken wings one day--thanks!--but otherwise it was up to you to rummage through the candy bar bin. The menu chalkboard next to the kitchen? At first, it just had a question mark on it, as if to heighten suspense. (Which there was, as on multiple occasions after peering at the plate set in front of me, I had to ask a member of the crew: "What exactly is this?") But then the question mark was erased and the board was just blank the rest of the trip.
4. Food: This was my fourth liveaboard, and always before the food has been consistently very good, occasionally amazing. On Valentina, it was consistently terrible with every once in a while rising to the level of decent. Every single meal was drowned in buckets of sauce, so much so that I was almost tempted to throw a PFD to the fish or the pork or whatever it might have been, to save it from drowning. Thankfully, one meal had a buffet so you could determine how much (or any) sauce to add, but only one meal, with the rest plated and drowning.
5. Doing their own thing: Want to be clear: the divemasters were very good and professional. But out of the water, the boat had a different feel. There's only one interior community area, for instance--the salon/dining room--but it was hard to spend much time in there because the kitchen guys were blasting heavy metal so loudly I couldn't even think, so I just went outside.
I previously went to Socorro on Rocio del Mar, which was a vastly superior experience.