If you feel confident that you can figure out basic mechanical things, the Z2 is by far the best option. I got my Prophecy used from someone who thought it was broken for dirt cheap (it kept jamming on him), and it turned out he had assembled it wrong letting something be a bit out of place and causing jams. 30 seconds and I fixed it, and it was LNIB. I had problems with the original Empire speedfeed that had the magnets exposed, but the newer on that has rubber covering the magnets has been problem free. It's lighter than the rotor, feeds faster than the rotor, and doesn't jam like the rotor. My teammate had a Rotor and kept trying to justify it to me, and after too many jams he just gave it up and bought a spire, which from what I've seen is another good choice. If you don't feel that you are competent enough to own a Z2, then go for the spire. Also, when the Rotor jams, it's usually a ball that got stuck between the two rotors, and if it was soft enough when it got wedged in there, your unjam trigger will jam too, making it impossible to fix without taking it apart. I would never want to be caught with my pants down on the field, and to say that worrying about jams is "nit-picking" is just silly.
Basically, the problems with the Rotor are oftentimes outside your control. You shoot the paint the store has for sale, and if you're playing a tournament in hot humid weather, your paint may not still be perfect by the end of the day. Sometimes you just can't control what paint you shoot. However you will ALWAYS control the abuse your hopper deals with. You are the one who would be responsible for overtightening the feedneck. You are the one who would be responsible for cleaning it and assembling it together properly. That's why I choose the Z2. All the big scary situations of "Oh noe! I put it together wrong!" are completely under your control. You just have to be competent. With the Rotor, you can do everything possible and still have a bad day.