RE: Doing some upgrades...
Rest - I would go with Limb Driver or Whammy. I have a whammy and have no regrets, but where I hunt is super thick and I didn't want the long Limb Driver string.
Sight - I have friends w/ G5 sights and they aren't too happy for what they paid. I have a Spot Hogg Wrapped Real Deal and love it. Great sight. Buddy just got one and loves his too.
It's all in what you like and have confidence in, like anything.