Gray last week announced he will leave Glasgow at the end of the season after agreeing a three-year deal with the Aviva Premiership side, before showing his commitment to the Warriors' cause with the match-winning try in the 26-21 Heineken Cup defeat of Bath.
Scotland attack coach Gregor Townsend enjoyed spells in England, France and South Africa and believes Gray will benefit from the move, despite previously hoping the lock would stay in Glasgow.
Former Scotland and British Lions back Townsend said: "Richie's motivation is to improve as a rugby player, which is great.
"That's why he's made that decision and I know it was a very tough decision for him.
"You really make the most of any move by the work you put in and the learning you get out of it - picking the brains of new coaches, testing yourself against different opposition and improving each time.
"I'm sure that's what he wants to do and I'm sure that's what will happen."
Former Scotland back-row Stuart Reid, who enjoyed a spell with Narbonne in France, encouraged the 22-year-old, who is 6ft 10in and 20st, to make the most of his chance.
Reid said: "It's unfortunate for the Scottish rugby public, but the world is that boy's oyster.
"I think he'll seize it with both hands and take the opportunity to play against the best there is."
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