Daimon was using Mindbender, which gave him 80k more mana to work with, which is about 1.5m healing for him with the 33 extra renews he got. That was a tiny bit more than you got from your SoL procs. We should count the serendipity stacks gained from the procs, but since you didn't use them, you lost a lot of the value from the talent. I wouldn't say that you should opt for Mindbender over SoL, but I would strongly consider Solace to be the most viable option here, especially with 4pc since it "devalues" the serendipity stacks you get from the Flash Heals. And with the 4th healer, I wouldnt say you wouldnt be able to fit the GCDs to cast Solace on CD.
(Advanced logging wasn't on, and I don't know if there's another way to easily check mana without the resource tab
)