Well got my 4T8 set last night, although I'm still using Valorous Nightsong Handguards but I will swap that out later :)
I saw a big jump in Rejuv heals (which is to be expected) from 8-13% to 20-25% but it also required a bit of a shift in my healing style or more specifically my spell prioritisation.
I dont think that my heals when I'm healing tanks (this is generally my assign) will change that much, I will have an extra tick and also (in theory) a bigger Swiftmend so that will be good for oh crap moments (like Ignis flame jets).
I'll use Mimiron as an example because this is a real all out, as Matt would say heads up method, and is a real indication of whether you've got your prioritisation right.
While healing I ask myself these questions in my head while i'm healing for Mimiron we are primarily looking at the right hand side of my little brain chart :)
In summary where there is raid damage being taken I decide if I'm expecting more damage in the next second or so, if so I get my 'best for the cast time' spell off, being Nourish.
If I'm not expecting more damage I choose regrowth, it has a slower cast time but does have the bonus of a hot.
If there is minimal damage or currently no raid damage I will use rejuv across the raid.
It's worth noting that throughout this process I am hitting Wild Growth whenever it is available and I can afford the use of a GCD :)
On the other side of the chart, my tank healing, I wont use Wild Growth too much on a boss encounter i either; dont know well enough, or I know is going to be a hard slog on mana (i.e. General).
On a side note I was promoted to a Sub Officer last night :) was pretty excited about the whole thing :)
On another side note, just a quick shoutout to Sydera who blog on World of Matticus who I noticed comment on my last post, I was excited to see your name there as I read your blog frequently :)