Allow me to counter everything youve said. Firstly well done for telling us what we already know even though youve overestimated the combination of sm + km way too much, but also youve only looked at naruto's possible abilities whilst ignoring sasuke's. Maybe because you are making an argument for naruto or maybe we havent fully seen what ems sasuke can do.
Anyway jiraiya already had trouble controlling his chakra whilst in sm thats why we saw his part transformation when he was in sm. Secondly we can argue that the reason naruto was able to withstand nagato's chakra in sm + km was because nagato was already extremely low on chakra, evident in the use of gedo rinne tensei which effectively killed him.
Secondly km modes combat abilities is extremely similar to sm and infact both side abilities is also similar. Km allows the user to extreme speed, durability, strength and almost infinate chakra. Sm gives the user the same thing, but in this case natural energy. The side ability of sm is to sense chakra, whilst the side ability of km is to sense evil thoughts. If naruto was to combine both, he would only increase what both already gives him, unless kishi pull something out of his ass off course.
You, say and i qoute; 'take chakra sensing, malice sensing, and sm's threat perception and add them together. which gives you a very early warning of opponents and attacks, people's intentions etc. ie it will be insanely hard to hit, naruto in sm has never even gotten hit let alone in both modes.'
Firstly being a chakra sensor isnt really a combat feat but rather a tracking feat. Thats isnt really useful in combat. You say malice sensing, well its a fight he doesnt need this ability to know that his opponent wants to kill him. He would also be on his guard regardless of this ability. None of this gives him an early advantage against opponents attacks as we saw against nagato and tobi, unless you are basically trying to say that he will get the same ability as spiderman, which he hasnt demonstrated. But also this ability doesnt leave even spiderman immune to attacks.
Sage mode katas is unique to sage mode. I do not believe that the combination of sm and km would allow for the use of sage mode katas because that combination isnt (sm+km) sage mode anymore. Lets say its possible, it is bound to take great concentration and probably another training arc.
Also you exaggerate about naruto having the sage's body. Firstly sm+ km doesnt give you the sage's body. The sage was able to not only surpress the ten tails chakra which is made up of 1-9 demons but also contain it. Naruto only has 1 of these demon chakra in him and even that its half the fox's chakra.
You say naruto was able to withstand damage from falling from huge hights therefore his body is basically 'invisble'. Although i agree that he did withstand damage from falling from huge hights, that doesnt mean ne is invisible. People seem to forget that naruto in km+sm was stabbed by nagato's chakra receivers. Also jiraiya in sm got not only his left arm taken off against pein, he got his throat shattered, chest stabbed and eventually stabbed in the back numerous times which in the end killed. These are all physical attack.
You do not want me to get into other types of attacks that would leave sm + km defenseless. What ive said is basically countering your argument for naruto and i havent even talked about sasuke's abilities
