I have played in the Newport and MGM HL rooms on occasion (mainly when I'm playing from behind) at various times of day and have not experienced too much heat spreading 10:1 or 12:1 (50-500/600).
That being said, I would hazard a guess that the HL rooms will definitely get sweatier now considering the vast difference in quality between the games outside and inside. Before the risk/reward wasn't really worth it to play in the HL rooms. Now, with generally less crowded tables, S17, 6 decks, and better pen, it will more than likely be worth it to play in the HL rooms as long as you make sure to have your heat radar up.