What do synergies give us?
Can they boost our skills above limit? No, they can't.
They allow us to put less skill points in skills and still have them at current skill limit.
With 4 in Will we can put 13 in all PSI schools and have this:
Thought Control 13 (15)
Psychokinesis 13 (15)
Metathermics 13 (15)
Putting more SPs would not give us anything.
Now, if we increase Will to 9 we will have this:
Thought Control 13 (18)
Psychokinesis 13 (18)
Metathermics 13 (18)
So far so good. But try putting more SPs in our skills. We will have this:
Thought Control 15 (21)
Psychokinesis 15 (21)
Metathermics 15 (21)
Previously we couldn't raise effective skill level by putting more than 13 points in any of three PSI skills. But now we can. Looks like bonus from synergies were overridden by high ability score bonus. Let's do one more test and remove points from 2 of our PSI schools:
Thought Control 0 (1)
Psychokinesis 15 (21)
Metathermics 0 (1)
Indeed, synergies have no effect if bonus from ability score is higher than their bonus. And this defeats their purpose.
I'd also like to notice that "typical" (for some definitions of typical) character build will put most of his skill points in skills that benefit from those ability scores that have high values.
What i would like to see is synergy bonus stacking with ability score bonus. Synergy bonus would be applied first, increasing skill level not higher than current limit, then ability bonus would kick in, possibly increasing it above limit.
In my example it would give us:
Thought Control 13 (21) ( 15 with synergy bonus only )
Psychokinesis 13 (21) ( 15 with synergy bonus only )
Metathermics 13 (21) ( 15 with synergy bonus only )
Investing more SPs would not increase effective skill level.
There are two thing to notice here:
Maximum effective skill level will remain the same.
The rule "synergies cannot boost skills beyond their maximum for your current level" will not be broken.
I wasn't sure if it's a bug or not so i'm putting it in Suggestions forum, just to be on safe side (: