I have gotten so used to having 9 gears that I think I would always miss it if I went back to a 5 or 6 gear.
However, with this many gears, you can't get the best driveability by letting the computer always decide when to shift. I have gotten very used to popping it into ERS mode and telling it which gear I want to be in.
We also got my fiancé a Renegade, so I have a chance to compare operation of the 9speef across models and model years. I like how the transmission is implemented in the Renegade even bette than in the Cherokee. It seems to be a bit more responsive, and manual mode is a true real manual mode. You select a gear, and the transmission shifts and stays in that gear. Very predictable performance this way, and you can always get into 9th if you want, you just start losing speed it conditions aren't not right for it.
More gears is apparently all the rage these days, but there are some practical reasons for it. Car manufacturers need to comply with stricter fuel standards now, and one of the ways they know they can do that without making many modifications to the engines themselves is through the transmission, and that is by giving it more gears.
Take a standard 6-speed transmissions, and compare that to the more recent 8 or 9 speed variants, and you'll likely see anywhere from 2-5mpg increase in fuel economy on the highway, which is huge. The trouble though with all these gears is complexity, so there's more to go wrong if something should go wrong, and it doesn't help that because the KL is a transverse-mounted engine, the transmission is space-starved compared to the 8-speed ZF in the Grand Cherokee. This added complexity, and lack of conventional means with all the clutches, and extra gears can certainly add to more potential problems, as many of us have all experienced. I don't however think the ZF9 is a fragile engine as some have said in the past. It's just finicky at times, but I think it's plenty durable to handle anything you throw at it.
And now, we have the new 10-speed transmission in Fords and GMs, which I've heard is quite good. One example is you can be in 10th gear, and if you floor it, it'll automatically downshift to maybe 5th gear for maximum performance. It's the same thing as downshifting from maybe 6th gear into 4th. Guess those transmissions can do that from my understanding.
But as we get better and better hybrids, and electric cars, the idea of a transmission might seem more of something in the past, as the proper old-fashioned manual transmission is now becoming. I'm actually surprised FCA hasn't implemented a hybrid Jeep yet, because that could turn out to be interesting. Unless of course FCA wants to have more diesel engines across the lineup (which they should to be honest. Why FCA haven't put the 3.0 ecodiesel in the Wrangler is beyond me).