I've had my X2 for about 3 months now, with the ludicrous upgrade. I see a lot of questions about speed. I will just say this is a mountain bike, not a motorcycle or street bike. It is geared like a mountain bike - for climbing - not for speed. I spent a couple weeks last month riding the trails in NC and it was fun. Mostly I was able to keep the assist in level 1 (of 5) in 750 watt mode to be able to keep up with my son riding a Transition higher end mountain bike. I'm 56 and weigh 260+ lbs. A few times I kicked it up to assist level 2 on the really long steep assents. We rode some decently long rides - Tsali (about 20 miles & 2100 ft of elevation gain), Fire mountain (multiple passes - ~8 miles and 1000 ft of gain), and Black Rock loop (14 miles and 2300 feet of gain) in Pisgah. I don't think I ever used more than 15% of the battery.
Higher power levels are just not needed unless you are just messing around. I still recommend the controller upgrade due to the programmability.
Even riding on a paved trail, I'm able to maintain an average of 15mph for over 15 miles in assist level 1. A 15-mile mostly flat paved ride in assist level 1 (of 5) while limited to 750 watts tends to use up about 10% battery. Just for fun, the other day I rode this 15-mile ride on assist level 2. It wasn't much of a workout, the average speed jumped up ~2mph, and used about 13% battery.
You can likely change out the chain ring and move to a 9-speed cassette for more street riding and higher speeds and less likely to break the chain. But if that is the goal, this isn't the right bike. In the NC community, e-mtb bikes are largely not welcomed or not allowed, mostly due to people tearing up the trails with higher power - riding like they would a motorcycle.