As for the second question in regards to durability and longevity all I would add is, why would you. The motor is strong enough and capable of turning a 50lb load, more than enough for a 23 inch span. You'd be hard pressed to reach those limits with food and equipment accessories, adding anything bigger would be overkill and unnecessary IMO. I've had my unit for some time, approx 7 years I believe. It's something you find useful but you don't use it all the time. I didn't like the chore of removing and installing the unit so I ended up leaving it on the KK while covering the unit with a piece of foil and a waterproof cover. The cost today is $67.99 for a 13 watt motor, nothing lasts forever but it's all you need.
I have used the basket splitter with a deflector resting on the two bars of the charcoal basket with adequate air flow to maintain a fire. If you were to use foil on the lower grate above the fire you air flow would be even better. I believe that was your question, if not that's how I interpreted it. All I will add to that is, the first set up on the handles has limited airflow so reaching higher temps can be difficult when using in tandem with the basket splitter.