Mine would cruise at 60 no problem. Started feel like it was working harder over 70. I don't think you're going to get a ton of pop if you're cruising over 60 mph and then roll on more power. It will climb but doesn't do it with authority at point. Based on memory, would say below 50 is where it's going to have pop but it's hard to say. Don't look at my gauge that much. Generally speaking , it cruises fine on long straights just fine but it's not going to be responsive like an 850. In the corners is where it has more authority. Just what it is.Here's the Snow-Tech article when it first came out, goes a little more in depth on the new engine.
Near as I can tell on the 600R I should be able to cruise at 60 and do upper mid-range roll-ons into the mid 70s versus my 850 which cruises at 70 and does roll-ons into the mid 80s.