Thanks for your comments!
We went on the April 22-30 trip. They market this as the last chance to see Humpbacks for the season. Although we saw tons on the surface and heard them loud and clear down below, they never graced us with their presence while diving - so we'll definitely be going back, for that and the killer whales and whale sharks - Solmar V offers great chances to see it all.
Of course I'll never pass up a chance to dive with the giant mantas and the bottlenose dolphins, but these sitings seem to be more of a guarantee than a chance!
Just don't forget the Bronine as the islands are spread apart and the night sailings can sometimes be rough. You want to be well rested for the full dive schedule the next day (3-4 dives w/. nitrox of course!)
Hopefully I'll see you out there!
Cheers,
James