I'm at 98 miles, and just around 6 hours on my bike after one week (literally took delivery last Monday). I have the Ludi X-1 and wanted to chime in on a couple of topics/issues that have been discussed.
Top speed. The bike is unquestionably gearing limited to 25MPH (on the 13T cog); the display shows the limiter set to 56 MPH. Working backward from some top speed runs with the stock 32T chainring and the 13T cog on the cassette, the M600 tops out at around 125 RPM on level ground. I built a chart (using bikecalc.com & PS) to compare 32T, 38T, and 40T chainring options. I have no doubt the G521 has the power to push well past 25 MPH. In fact, I adjusted my derailleur so that I can access the 11T cog and hit just over 30 MPH in a light headwind. I didn't want to push it too hard because it will skip, and I don't want to destroy the cog. Here's the chart in case anyone wants to use it to make a decision on chainring upgrades.
Last comment on the top speed would be that if you bought this bike to ride on the road (or really even on "bike path" type trails), I'm not that surprised at your disappointment. There isn't room on the frame for a large chainring, and that makes perfect sense to me. The bike is clearly designed for off-road applications. That doesn't mean you shouldn't be disappointed; it just means you probably wanted another bike and maybe didn't realize it. Apollo anyone?
PAS. On-road (riding to/from trails), the PAS has been a little goofy for me. I think it's a combination of two factors: 1) the PAS seems tuned for off-road, and 2) the Ludicrous "hack". Luna shunted the controller to achieve the higher power levels. Word is they also got a custom firmware. I don't want to speak with authority here, because this is all just "what I've heard", but IMO, it explains some of the PAS's characteristics. On-road, using PAS 2/5, there's a "break-over" input torque level where the assistance jumps. It's right around 15 mph on the 13T cog. This goes away if you move up to PAS 3/5, or if you change gears. It's an idiosyncrasy I'm happy to live with because of what I'm about to cover next.
Off-road, the PAS is incredible. I'm in South Florida, so the trails I ride are pretty soft. There are a lot of sandy patches mixed with matts of pine needles or mangrove seeds. It's all either soggy, spongy, or sandy. With PAS 3/5, I can ride 12-18 MPH through trails with an avg heart rate of 130 bpm. That couldn't be better for my use case. I feel like I'm flying, and I have a throttle there to carry me through sandy berms, so I can hang a foot out motocross style to catch myself when the sand occasionally gives way out front.
As far as wattage, I probably don't need to explain to everyone here what a shit show wattage ratings are.
Bafang calls it a 500W drive, but I've seen well past that on my display when pulling up a sandy climb. It's worth noting that the way Luna shunts the controller, the display shows the "normal" wattage value, but double the amperage provided to the motor. So if you see 250W on the display, 500W is being sent to the motor. I have a feeling this contributes to some of the PAS goofiness on-road. Off-road it gets soaked up by the terrain. I'd be curious to hear some PAS impressions from 750W riders. The base controller is 20A, so doubled is 40A. If you do the math, 48V * 40A is 1920W, which is where Luna comes up with the 2000W number. Is that a "real" number. No, of course it's not. The real number is what the motor draws on the trail, but if the controller is able to supply up to 40A, it's not unreasonable to "rate" the bike that way.
Noise.
Yes, you can hear the motor when it's operating. How loud is it? Well, that depends. Under PAS, I don't find it loud at all. When operating RPM is at human cadence levels (≤85 RPM), the motor is barely noticeable. Lean on the throttle and push +1000W to the motor at ≥85 RPM, and it starts to whine. More power means more amplitude (sound waves). It seems inevitable that it will be louder. I'd imagine that the 750W version is a bit quieter, as it's not being hit with as many amps. If you want a really quiet bike, do a big wattage hub-motor build. The gear reduction in a mid-drive is going to make noise, and when you put in metal gears for durability, that makes matters worse (or better, depending upon your priorities).
Where the bike shines. Get this bike off-road and cover some ground and you'll discover exactly what this bike was built for. I came from a hardtail, so you can water down my enthusiasm if you wish, but this bike rides like a magic carpet. The suspension soaks up every single thing I've thrown at it. Seeing that I'm in Florida, I'm not doing any rocky downhill work, but my trails are 100% un-groomed. They're natural Florida scrub. I'm dealing with pine tree roots, random saw palmetto trunks, the occasional fallen tree, and a gator tail here and there

Seriously, I have scared the hell out of a couple of baby gators coming up on them so quick. The X-1 has eaten everything I've thrown at it. The biggest 1st world problem I have is that the massive derailleur likes to wind up grass and weeds around the lower pulley. I didn't have this problem on my old Deore derailleur, but then again, that was an old 3-by-9 setup. I'll take the 1-by setup and avoid the super grassy stuff, thanks.
The X-1 is a very focused bike. It is un-compromised for off-road use, which makes it extremely compromised for on-road duty. Riding this bike on-road is like trying to run the Le Mans 24hrs in an Ultra 4 Trophy truck. Weird flex, but OK :lol:
I weighed mine at ~55 lbs (54.5 lbs to 54.8 lbs, but I won't split hairs). By comparison, a Biktrix Jugg FS is 72 lbs and costs more when you up spec the fork to a Rockshox product. A full carbon Specialized Turbo Levo is 48 lbs, but it has a 500Wh battery and no option to double your power output. Oh, and it's nearly $10k. It strikes me as a little bit on the insane side that there's even a discussion of whether the X-1 is a great bike. I get it that some people might not have understood the bike, but once the intent is clear, I think there's no debate. The X-1 is an incredible bike at an unbelievable price point.