Highly tuneable very easily and the newer systems (which are impractical to retrofit due to direct injection) allow you to laten the ignition timing and compression ratio for increased power and have 'super lean' modes at idle and part throttle for good fuel economy too.
A well setup bank of carbs can work really quite efficently across the whole rev-range and if you want to avoid the CVK 'lag' then you can always go for an FCR type carb.
Since the 30 is so old and built for carbs I wouldn't bother with FI unless it was a highly strung out track bike and you were trying to get every last drop out of it.. but then again that'd be only for a '400' class race bike for me, as the amount of time money and effort it would cost i'd just buy a more powerful bike
Contrary to many urban legends, especially by die hard 400 enthusaists, many who've not ridden the bikes themselves, some of the new 600cc bikes handle better than the 400's and have much more power.
I don't think many people find the stock throttle response and engine performance from a correctly running nc30 to be a problem?