Borat, with your "Frankenturbo", would you do it all the same if you were to do it again? Should I take this opportunity to mod anything else? My mate will help with electrical mods but I don't want to be ringing him with "just one more thing if you can" type requests - I'd rather give him the list up-front.
I find that 1kg is a sweet spot for me in more ways than one. It's almost a set and forget on my KKTO setup, as the larger roast size with the mod means after the preheat, you just switch the element on and wait until 1C before you need to intervene and do something.
Also a 1kg roast easily fits into 2x 500gm bags and lasts me about a week or a week and a half. As soon as one bag is gone, I go out and roast another kilo.
If I get lazy, or forget until I'm out of beans, I'll roast 2x 1kg batches. By the time the first kg is gone, the other bags are already good for drinking...
So coming back to your question, is there anything else on my setup that I'd mod - not really. Bigger roast batches are only good for me if I happen to be doing more for somebody else. So I can deal with the limitation of somewhere around a kilo, as it suits my requirements 90% of the time.
You'll need to put in some type of chaff slits. I actually never tried the pots without slits so I can't say how well it works without them - but it does do a good job with them.
Don't foget to buy a stainless type thermocouple (KK will tell you how to get one), and mount it on the base of the inner pot. All you need is a small self tapping screw, and a couple of bits of wire to secure the braid on its run up the side of the pot. If you get a CS meter, don't bother with the style stick type probe as its a pain in the backside and you don't want to be drilling holes through the side of your pots.
And set yourself up with a combo vac / cooler system so you can just vac the beans straight out of the pot and into the cooler, instead of buggerising around tipping out hot beans.