In your opinion, the benefits far outweigh the disadvantages?

Benefits: stability, grip, looks

Disadvantages: acceleration, braking, comfort, fuel consumption

Rims are kind of the 'last' mod that I will do to my car. Already did:

Full braking system (steel-braided hose, slotted rotors, performance pads)
Stage 1 UR bars
Full exhaust system mod (extractor, piping, bullet, muffler, tip)
Low-resistance cables
Voltage stabilizer
Stiff rings (front and back)

Just a 2012 Myvi 1.5 SE.

Nah, just listed the mods down as I could remember them.
Yup, already went for it. Advanti Storm S1 + Michelin PS3 195/55/R15

Loving them so far despite the sacrifice in comfort.