'The needle jets are what has the most effect just off idle. '
I suggest 'just off idle' is the throttle opening at which the slide cutaway and pilots usually have most effect. The needles, and needle jet sizes have more effect over 1/4 and up to 3/4 throttle. If you have a look at the three stages of taper on a mikuni needle as you open the throttle while looking down the carburettor, you will see where the shape of the needle has effect. At 1/4 throttle, I believe you would be metering on the parallel part of the needle, and the provision for mixture adjustment is elsewhere. If your needles are higher to get the mixture rich enough at 1/4 throttle, your mixture is probably too rich at greater throttle openings until the metering is done by the main jet. It affects the way the bike behaves on roads with a lot of tight corners, the mid-range response. On two strokes, it can be a disaster, on four strokes you get away with a lot.
It helps to put a spot of paint on the twist grip at 1/4 and 3/4 throttle, and get accustomed to the feel at those two openings while the bike is stopped. When you are riding the bike you cannot look at the paint spots , but you can estimate your throttle opening from experience. If you lower the needles one notch, the motor should cough at about 3/4 throtlle when riding the bike around the twisty stuff. Every where else , it should be a blurr. Setting the low range is fairly easy if you've got a few alternate pilot jets, and I wouldn't bother to change the slides. Setting the mains is also easy if you use warmer plugs and do a plug chop on a cold day on a long fast piece of road. When I set the idle, if the screw adjusts fuel, I simply turn it in until the motor coughs then back it off 1/4 turn. If it adjusts air, the reverse applies.
I would get the needles and the idle set right first then try a few different pilot jets to get the transition from idle to needles right. Do the mains last.
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