Rear shocks

[Flynbulldog_imp]

lowering the rear end will adversely affect the handling and safety.
It will turn more sluggishly, require more effort and be less stable at speed.
Raising the rear will make the bike more nimble and turn more quickly.
Raising the rear too much can make it twitchy and prone to head-shake

The front and rear must be raised and lowered together to retain the correct handling.

If I were adjusting the bike for performance I'd raise the rear about 10mm.

If I were trying to gain better reach to the ground I'd start with the seat and leave the suspension alone.