1- I'm pleased to see that Gib decides to escape to a safer contract in facing intimidation of penalty double.
2- Gib shouldn't give up the choice of 4♣ - 8-card suit fit as a better contract because the purpose of bidding is just looking for 8+cards suit fit.
3- In most of situations, expecially contest sequences, the original hand evaluation can't upgrade to higher with increasing levels of contest auction.
See the explanations on 5♣ and Gib N's double.