I think All Virus range use the same keybed (Fatar) semi weighted...and they are bliss to play
Not exactly. Virus C Indigo 2 and TI Polar have different keys. Polar has weighted heys with metal plates on the back whereas Indigo 2 does not. Also their form factor is different and cannot be inter replaced. Also as far as I know Indigo 1 and indigo 2 keys are also form factor different.