I am going to order a Neu motor soon...1515 2.5 1700kv for my maxx...opinions

[VintageMA]

What ESC are you planning to run? If you are going to the MMM then you could consider up to 6S for a very efficient system with cool long runtimes.

1515/2D (2050kv) - 4S @ ~5000mAh (74W/hr) (30,340rpm)
1515/2.5D (1650kv) - 5S @ ~3900mAh (72.15W/hr) (30,525rpm)
1515/1.5Y (1500kv) - 6S @ ~3300mAh (73.26W/hr) (33,300rpm)

As you can see all 3 combinations have about the same rpms, the same Watt-hour capacity and about the same battery weight. Yet the 6S setup will be the most efficient and coolest running.