I have a 3GR too and it's ace, no more crystals
. This is what I've done with mine:
1. Throttle EPA reduced from 100% to 85%, different motors/speedo's will need more or less but if you leave it on the default 100% setting you'll probably spin out as soon as you think about braking.
2. Steering EPA - set it so that your steering arms just stop short of hitting the arms on full lock, this avoids stressing the servo unnecessarily.
Everything else is down to preference. If you have a nitro car you can set the brake mix for example. If you have more than one car you can assign each one a specific model memory (max 10 different memories) with a name for each.
The 3GR is well worth the money particularly for electric cars in my opinion as the top sets like the 3VCS are only worth the massive extra price if you have a nitro/petrol car.