I wouldn't say that it would boost their intelligence, but it does seems to help them strategically with its multitude of senor abilities and its own basic instinct.
For example, in the 2005 TV series, where Sho and Tetsuro are brought to the warehouse, and the gun accidentally goes off while aimed in Tetsuro's direction. The unit recognized the threat, towards Tetsuro, who is Sho's friend, and destroyed it. Sho wasn't in control of the situation, but the unit was able to react for him.
I assume in some other cases, this might be how it taught Sho how to use it. Momentarily taking control of him in order to do something, or use a weapon that Sho does not know of yet. We do know the unit is alive, but seems to be more instinct, rather than sentience.
I.E. Sense threat -> Destroy Threat using best ability available. Overkill guaranteed. For example, Megasmasher vs Vamore. Who could have just as easily been taken out by a quick head shot from the head beam. Finesse is not in the units strong point. Completely obliterating the threat certainly is. And it seems to try and react "In kind" depending on the threat. Like when the unit first bonds with Sho. All Gregore does it try grabbing it, and it responds by grabbing back. Then over powering. It could have easily fired off its head beam and finished Gregore off in an instant. Or with Synevite and using the HF swords. Melee vs Melee.
So basically whenever Sho is against something that the unit can counter, and Sho doesn't know about, it'll probably just take over and do it, to protect itself and it's host, all the while showing the host a new ability.
It probably played a big part in Sho using the Exceed as well.
But as for making them more intelligent? Not necessarily.
Does it make them more strategic? Mentally? Probably not. But it certainly helps in a lot of situations.
Unless you count being tossed into a war with an international company who now controls the entire world, forcing them to learn how to survive, and create tactics to basically survive (and turns out, Sho is very adept at doing so!)