I think one thing that might actually be a concern is people having all the time they want to explore the maps. Pro: Honest players will be able to get to know the maps better, as there are no bullets flying at them at every moment. I'd definitely take a good tour of new maps before jumping into crucible. Con: Dishonest players will be able to more easily find the glitch spots in maps that give them certain unfair advantages like headglitch spots and getting outside the intended playing area of the map. They will definitely come back to public matchmaking and exploit all the glitches they found and a much faster rate than we've ever seen. I imagine every map still has one or two undiscovered glitches that require more time to figure out and setting up your own private matches definitely gives you the time to do that. Pro: More glitch exploitation [should] equal quicker patches from Bungie, although it does mean they will need to work faster at patching things than they have in the past.