Good points!
Of course too sharp of a downward angle may get the inside V angle under 90 degrees which will effect the feedpoint impedance. I would use 4ft metal stakes driven deep with ratchet straps to hook onto the antenna ends to get it real taut. The counter weight looks good enough if it was on a tight line.
That is a rather thick diameter mastrant guy rope supplied with this antenna. I use a thin 1/8 diameter mastrant rope on my inverted V and has a 800 lb break strength so the one I see with this antenna should be rated over 1500 lbs so it can be pulled very tight since it's not holding up very much weight.
Another thing to consider is people who live in cold winter climates will get ice on it that may last for days and weeks rendering the antenna useless. Then again, beam antennas have the same problem being stuck in position till the ice melts enough for the rotor to break it free.
Also wonder if there is any maintenance like grease on motor bearings/pulley shaft because like you said this antenna is dependent on the quality of the motor/components that is a concern because I see no warranty on this product.