Probably a case of not too many flying the X-8 since many in this forum are flying heavy lifter for cinema type work while others are overly enamored by the advertising dollars being spent by DJI that try to compensate for a lack of reliability. OTH, I fly one and have found it to be a very capable "medium lift" copter with a lot of features that can be pretty useful given the interface between Pixhawk and Mission Planner. To date Pixhawk has functioned perfectly in the X-8 and another home built quad, blowing an A2 out the door where flight performance is concerned. Then again, the A2 elected to crash itself so that may not be a fair comparison. Having 6 flight modes available at any given time, that can be interchanged with any of several other flight modes after connecting to Mission Planner and performing simple mode selections, is quite versatile. Even those can be customized a little further to simplify how things work but be advised using the "simple" and "super simple" flight modes comes at a price. One can become much too complacent in their flying since the Pixhawk system provides for a lot more ease of flying than many other systems.
Flight times using the 6000mA battery supplied by 3dR runs about 10 minutes or so depending on how you load up the copter. That time might be extended a bit using better propellers than the APC's provided with the copter but I haven't had the time to experiment with that yet. I run an FPV camera and carry a Go Pro on a Tarot 2D gimble with mine. I power the FPV and minimOSD using a 900mA battery to take the load off of the flight battery. You can run both the FPV and gimbal off the flight battery if you want and eliminate the second battery, I've done it both ways. Flight time drops to about 9-1/2 minutes or so doing that. "Factory" equipment wise the only complaint I had was with the stock video antennas. In a word they suck but changing them out for Blue beam stuff correct that. Moving the video TX to a landing gear leg to re-orient the antenna helps the broadcast range as well.
I really don't know what the maximum lift capability is with the X-8 but I do know it's a lot more than I'm carrying. It's not a light copter in and of itself but it can do a lot more than I'm asking of it. I know of two others that are flying the X-8 and neither of them has had any complaints. They are flying the copter with considerably different payloads, with one of them actually fitting a Black Magic pocket cam and custom 3 axis gimbal to his while the other has slightly modified the FPV system to get out there quite a ways using 433mHz. The system has a lot of failsafes the user can set up to protect from fly aways or low voltages, etc., but the user MUST take the time to learn about them and how to set them up within the system. It's a very intelligent system but the user cannot be "dumb" about it and expect to make full use of its capabilities. There's a lot of reading that needs be done to truly exploit what the flight controller can do, but all that info is easily accessible, along with the software that drives the systems if one is both inclined and has the ability to make use of an open source code.
At least for me and the two other people I mentioned the X-8 has turned out to be several things I like very much. Capable, reliable, flexible, and robust. It doesn't hurt that 3D Robotics has been extremely responsive to info inquiries and after sale support with some accessory product issues I had early on. Even better is the info available at APM Copter and through the Wiki pages provided as learning tools. I don't know that anyone could ask for more from a company or their products than what they have thus far provided. I would absolutely buy another.