The rear is EPIC compared to the stock gen3/4 sedan setup i had in the rear. (The OEM gen3 wagon setup was SO different in its own way. The rear springs were easily 3 times bigger than the gen3/4 sedan springs and progressive rate. My dad accidentaly thew out the springs i had stored at his house so i had to buy a new setup) I can now go up to 70+ km/h in curves i could barely go 50 and my shocks in front are blown. It's that much of a difference.
Most of that is due to the TRD RSB though ( i keep it at the stiffer race setting). The wagon even seems almost tail happy because of the stiff rear. I love it up to now.
From what i heard of the complete setup its gonna be pretty stiff. Can't really say much on ride quality yet because of blown fronts.
IMHO, you should get the TRD rear struts from gregtrd on solaraguy and buy 4cylcthriller's tokico's for the front and reuse his eibach for the rear. Since you have a gen4, a tower bar or beefier front sway bar would negate any advantage of having bilstein /TRD's at all 4 wheels and would make for a comfier ride without sacrificing too much handling.
Your suspension options are:
Cheapest : Tokico/Eibach Setup 400$ from 4cylthriller
Great : Tokico/Eibach in front w/ TRD/Eibach in rear from 4cylthriller and gregtrd 520$
Best : TRD/Bilstein at all 4 wheels...
Coilovers could be the same price or even cheaper than having a complete bilstein/eibach setup.
I personally don't mind having german engineering in my vehicule. It's already a US made car with Japanese design and chinese parts everywhere