Regarding the Mixing of Different Servo Models for the SR6

My budget is very limited, so I plan to mix cheaper servos: use GX3225 (25kg) servos on the four main aileron/elevator channels, a 996R servo (13kg) for the pitch-control servo, and another 996R for the rotation servo. Will this work? or should I save more for 6 Servo pack?

I would also like to ask some questions about servo selection. How do response speed, centering accuracy, and torque respectively affect the flying experience? (I am using a Tomax Venus, 637g.) Among the following servos – PTK6820, PTK6830, PTK6835, and GX3225 – all are within my budget. The first three have centering issues but are relatively fast in response, while the GX3225 is not outstanding in response. How should I choose? Or should I double my servo budget for brushless options, or add 50% for coreless motors instead?