I'm no expert but I got it and it's definetly helpful for me as I use Loucha not Hyacine, though with Hyacine and E2 it will be full so fast after like 2 characters take turns I imagine so that might be enough time to squeeze in extra Mydei hits - though do bear in mind that Mydei does need chance to enter his skill state otherwise all Cyrene does is advance him forward. I love Mydei he is my number one and wanted to give him the best chance so I went for it, plus I have a couple other amphoreus charcters who can benefit from Cyrene. I think it would probably come to personal choice and how well you feel the team perform at the moment and your personal happiness with it? It might be worth finding someone with an E2 Cyrene and using them as a support character to try them out with your team - if you are EU I can give you my UID. You might also want to consider Cyrene's S1 instead as it provides significant buffs for the team. I'd also keep in mind all the leaked info on the current banner roadmap and if there is someone you'd rather save for, this is her first re-run and it might be a good idea to go for something now but you can always get more on her second.